diff --git a/chartkit/src/lib/components/BarChart.tsx b/chartkit/src/lib/components/BarChart.tsx
index b671367..64f9de4 100644
--- a/chartkit/src/lib/components/BarChart.tsx
+++ b/chartkit/src/lib/components/BarChart.tsx
@@ -1,10 +1,10 @@
 import { useQuery } from "../useQuery";
 import { formatChartKitDisplayValue } from "../format";
-import { asNumber, asString } from "./utils";
 import { chartKitTooltipBase } from "./chartTooltip";
 import { echarts, ReactEChartsCore } from "./echartsCore";
 import { themeVars } from "./themeVars";
 import { useChartKitNamespace } from "./useChartKitNamespace";
+import { useChartSeries } from "./useChartSeries";
 
 export interface BarChartProps {
   namespace: string;
@@ -39,6 +39,16 @@ export function BarChart({
 }: BarChartProps) {
   const theme = useChartKitNamespace(namespace).theme;
   const { loading, error, rows } = useQuery(namespace, data);
+  const { xLabels, rankedSeries } = useChartSeries({
+    rows,
+    xValueField,
+    xLabelField,
+    yValueField,
+    yLabelField,
+    yAxisTitle,
+    seriesValueField,
+    seriesLabelField,
+  });
 
   if (loading) {
     return <div className="ck-inline-status">Loading...</div>;
@@ -46,53 +56,10 @@ export function BarChart({
   if (error) {
     return <div className="ck-inline-status">Error: {error}</div>;
   }
-
-  const xValues = new Map<string, string>();
-  const seriesLabels = new Map<string, string>();
-  const matrix = new Map<string, Map<string, number>>();
-
-  for (const row of rows) {
-    const xValue = asString(row[xValueField]);
-    const xLabelCandidate = xLabelField ? asString(row[xLabelField]) : "";
-    const xLabel = xLabelCandidate || xValue;
-    if (!xValues.has(xValue)) {
-      xValues.set(xValue, xLabel);
-    }
-
-    const seriesValue = seriesValueField ? asString(row[seriesValueField]) : "__single";
-    const seriesLabelCandidate = seriesLabelField ? asString(row[seriesLabelField]) : "";
-    const fallbackSeriesLabel = yAxisTitle ?? yLabelField ?? "Value";
-    const seriesLabel = seriesValueField
-      ? seriesLabelCandidate || seriesValue
-      : fallbackSeriesLabel;
-    if (!seriesLabels.has(seriesValue)) {
-      seriesLabels.set(seriesValue, seriesLabel);
-    }
-
-    const yValue = asNumber(row[yValueField]);
-    const currentSeries = matrix.get(seriesValue) ?? new Map<string, number>();
-    currentSeries.set(xValue, (currentSeries.get(xValue) ?? 0) + yValue);
-    matrix.set(seriesValue, currentSeries);
-  }
-
-  const xKeys = Array.from(xValues.keys());
-  const xLabels = xKeys.map((key) => xValues.get(key) ?? key);
   const shouldRotate = xLabels.length > 8 || xLabels.some((label) => label.length > 10);
   const valueFmt = yFmt ?? fmt;
   const palette = theme.charts.palette;
 
-  const rankedSeries = Array.from(seriesLabels.entries())
-    .map(([seriesKey, seriesName]) => ({
-      seriesKey,
-      seriesName,
-      values: xKeys.map((xKey) => matrix.get(seriesKey)?.get(xKey) ?? 0),
-    }))
-    .map((entry) => ({
-      ...entry,
-      total: entry.values.reduce((sum, value) => sum + value, 0),
-    }))
-    .sort((left, right) => right.total - left.total || left.seriesName.localeCompare(right.seriesName));
-
   const series = rankedSeries.map(({ seriesName, values }, index) => ({
     name: seriesName,
     type: "bar",
diff --git a/chartkit/src/lib/components/DataTable.tsx b/chartkit/src/lib/components/DataTable.tsx
index dc39730..b52599b 100644
--- a/chartkit/src/lib/components/DataTable.tsx
+++ b/chartkit/src/lib/components/DataTable.tsx
@@ -1,6 +1,6 @@
 import { Children, isValidElement, type ReactNode } from "react";
 import { useQuery } from "../useQuery";
-import { formatChartKitDisplayValue } from "../format";
+import { formatChartKitDisplayValue, formatChartKitNumber } from "../format";
 import type { DataTableColumnDefinition } from "../runtime/definitions";
 import { DataColumn, type DataColumnProps } from "./DataColumn";
 import { OverflowTooltip } from "./OverflowTooltip";
@@ -85,13 +85,10 @@ export function DataTable({ namespace, data, columns, children }: DataTableProps
     }
     if (typeof value === "number") {
       const fractionDigits = Number.isInteger(value) ? 0 : 2;
-      return value.toLocaleString("en-AU", {
-        minimumFractionDigits: fractionDigits,
-        maximumFractionDigits: fractionDigits,
-      });
+      return formatChartKitNumber(value, `num${fractionDigits}`);
     }
     if (typeof value === "bigint") {
-      return value.toLocaleString("en-AU");
+      return formatChartKitNumber(Number(value), "num0");
     }
     return asString(value);
   };
diff --git a/chartkit/src/lib/components/LineChart.tsx b/chartkit/src/lib/components/LineChart.tsx
index f4a161c..f73975b 100644
--- a/chartkit/src/lib/components/LineChart.tsx
+++ b/chartkit/src/lib/components/LineChart.tsx
@@ -1,10 +1,10 @@
 import { useQuery } from "../useQuery";
 import { formatChartKitDisplayValue } from "../format";
-import { asNumber, asString } from "./utils";
 import { chartKitTooltipBase } from "./chartTooltip";
 import { echarts, ReactEChartsCore } from "./echartsCore";
 import { themeVars } from "./themeVars";
 import { useChartKitNamespace } from "./useChartKitNamespace";
+import { useChartSeries } from "./useChartSeries";
 
 export interface LineChartProps {
   namespace: string;
@@ -37,6 +37,16 @@ export function LineChart({
 }: LineChartProps) {
   const theme = useChartKitNamespace(namespace).theme;
   const { loading, error, rows } = useQuery(namespace, data);
+  const { xLabels, rankedSeries } = useChartSeries({
+    rows,
+    xValueField,
+    xLabelField,
+    yValueField,
+    yLabelField,
+    yAxisTitle,
+    seriesValueField,
+    seriesLabelField,
+  });
 
   if (loading) {
     return <div className="ck-inline-status">Loading...</div>;
@@ -44,53 +54,10 @@ export function LineChart({
   if (error) {
     return <div className="ck-inline-status">Error: {error}</div>;
   }
-
-  const xValues = new Map<string, string>();
-  const seriesLabels = new Map<string, string>();
-  const matrix = new Map<string, Map<string, number>>();
-
-  for (const row of rows) {
-    const xValue = asString(row[xValueField]);
-    const xLabelCandidate = xLabelField ? asString(row[xLabelField]) : "";
-    const xLabel = xLabelCandidate || xValue;
-    if (!xValues.has(xValue)) {
-      xValues.set(xValue, xLabel);
-    }
-
-    const seriesValue = seriesValueField ? asString(row[seriesValueField]) : "__single";
-    const seriesLabelCandidate = seriesLabelField ? asString(row[seriesLabelField]) : "";
-    const fallbackSeriesLabel = yAxisTitle ?? yLabelField ?? "Value";
-    const seriesLabel = seriesValueField
-      ? seriesLabelCandidate || seriesValue
-      : fallbackSeriesLabel;
-    if (!seriesLabels.has(seriesValue)) {
-      seriesLabels.set(seriesValue, seriesLabel);
-    }
-
-    const yValue = asNumber(row[yValueField]);
-    const currentSeries = matrix.get(seriesValue) ?? new Map<string, number>();
-    currentSeries.set(xValue, (currentSeries.get(xValue) ?? 0) + yValue);
-    matrix.set(seriesValue, currentSeries);
-  }
-
-  const xKeys = Array.from(xValues.keys());
-  const xLabels = xKeys.map((key) => xValues.get(key) ?? key);
   const shouldRotate = xLabels.length > 10 || xLabels.some((label) => label.length > 11);
   const valueFmt = yFmt ?? fmt;
   const palette = theme.charts.palette;
 
-  const rankedSeries = Array.from(seriesLabels.entries())
-    .map(([seriesKey, seriesName]) => ({
-      seriesKey,
-      seriesName,
-      values: xKeys.map((xKey) => matrix.get(seriesKey)?.get(xKey) ?? 0),
-    }))
-    .map((entry) => ({
-      ...entry,
-      total: entry.values.reduce((sum, value) => sum + value, 0),
-    }))
-    .sort((left, right) => right.total - left.total || left.seriesName.localeCompare(right.seriesName));
-
   const series = rankedSeries.map(({ seriesName, values }, index) => {
     const color = palette[index % palette.length];
 
diff --git a/chartkit/src/lib/components/useChartSeries.ts b/chartkit/src/lib/components/useChartSeries.ts
new file mode 100644
index 0000000..dcc95b6
--- /dev/null
+++ b/chartkit/src/lib/components/useChartSeries.ts
@@ -0,0 +1,97 @@
+import { useMemo } from "react";
+import { asNumber, asString } from "./utils";
+
+export interface ChartSeriesEntry {
+  seriesKey: string;
+  seriesName: string;
+  values: number[];
+  total: number;
+}
+
+export interface ChartSeriesResult {
+  xKeys: string[];
+  xLabels: string[];
+  rankedSeries: ChartSeriesEntry[];
+}
+
+interface ChartSeriesOptions {
+  rows: Array<Record<string, unknown>>;
+  xValueField: string;
+  xLabelField?: string;
+  yValueField: string;
+  yLabelField?: string;
+  yAxisTitle?: string;
+  seriesValueField?: string;
+  seriesLabelField?: string;
+}
+
+function pivotRows(options: ChartSeriesOptions): ChartSeriesResult {
+  const {
+    rows,
+    xValueField,
+    xLabelField,
+    yValueField,
+    yLabelField,
+    yAxisTitle,
+    seriesValueField,
+    seriesLabelField,
+  } = options;
+
+  const xValues = new Map<string, string>();
+  const seriesLabels = new Map<string, string>();
+  const matrix = new Map<string, Map<string, number>>();
+
+  for (const row of rows) {
+    const xValue = asString(row[xValueField]);
+    const xLabelCandidate = xLabelField ? asString(row[xLabelField]) : "";
+    const xLabel = xLabelCandidate || xValue;
+    if (!xValues.has(xValue)) {
+      xValues.set(xValue, xLabel);
+    }
+
+    const seriesValue = seriesValueField ? asString(row[seriesValueField]) : "__single";
+    const seriesLabelCandidate = seriesLabelField ? asString(row[seriesLabelField]) : "";
+    const fallbackSeriesLabel = yAxisTitle ?? yLabelField ?? "Value";
+    const seriesLabel = seriesValueField
+      ? seriesLabelCandidate || seriesValue
+      : fallbackSeriesLabel;
+    if (!seriesLabels.has(seriesValue)) {
+      seriesLabels.set(seriesValue, seriesLabel);
+    }
+
+    const yValue = asNumber(row[yValueField]);
+    const currentSeries = matrix.get(seriesValue) ?? new Map<string, number>();
+    currentSeries.set(xValue, (currentSeries.get(xValue) ?? 0) + yValue);
+    matrix.set(seriesValue, currentSeries);
+  }
+
+  const xKeys = Array.from(xValues.keys());
+  const xLabels = xKeys.map((key) => xValues.get(key) ?? key);
+
+  const rankedSeries = Array.from(seriesLabels.entries())
+    .map(([seriesKey, seriesName]) => ({
+      seriesKey,
+      seriesName,
+      values: xKeys.map((xKey) => matrix.get(seriesKey)?.get(xKey) ?? 0),
+    }))
+    .map((entry) => ({
+      ...entry,
+      total: entry.values.reduce((sum, value) => sum + value, 0),
+    }))
+    .sort((left, right) => right.total - left.total || left.seriesName.localeCompare(right.seriesName));
+
+  return { xKeys, xLabels, rankedSeries };
+}
+
+export function useChartSeries(options: ChartSeriesOptions): ChartSeriesResult {
+  return useMemo(() => pivotRows(options), [
+    options.rows,
+    options.xValueField,
+    options.xLabelField,
+    options.yValueField,
+    options.yLabelField,
+    options.yAxisTitle,
+    options.seriesValueField,
+    options.seriesLabelField,
+  ]);
+}
diff --git a/chartkit/src/lib/format.ts b/chartkit/src/lib/format.ts
index c6d53da..0cb5d40 100644
--- a/chartkit/src/lib/format.ts
+++ b/chartkit/src/lib/format.ts
@@ -2,6 +2,18 @@ export type ChartKitFmt = string | undefined;
 
 const LOCALE = "en-AU";
 
+const formatterCache = new Map<string, Intl.NumberFormat>();
+
+function cachedFormatter(options: Intl.NumberFormatOptions): Intl.NumberFormat {
+  const key = JSON.stringify(options);
+  let fmt = formatterCache.get(key);
+  if (!fmt) {
+    fmt = new Intl.NumberFormat(LOCALE, options);
+    formatterCache.set(key, fmt);
+  }
+  return fmt;
+}
+
 function parseDecimals(fmt: string, prefix: string): number | null {
   if (!fmt.startsWith(prefix)) {
     return null;
@@ -47,14 +59,14 @@ function parseCurrencyThousandsToken(
 }
 
 function formatCompactNumber(value: number): string {
-  return new Intl.NumberFormat(LOCALE, {
+  return cachedFormatter({
     notation: "compact",
     maximumFractionDigits: 1,
   }).format(value);
 }
 
 function formatCurrency(value: number, currency: "AUD" | "USD", decimals: number): string {
-  return new Intl.NumberFormat(LOCALE, {
+  return cachedFormatter({
     style: "currency",
     currency,
     minimumFractionDigits: decimals,
@@ -75,13 +87,13 @@ export function formatChartKitNumber(value: number, fmt?: ChartKitFmt): string {
     return `US$${value.toFixed(1)}B`;
   }
   if (fmt === "currency_usd_m") {
-    return `US$${value.toLocaleString(LOCALE, { maximumFractionDigits: 0 })}M`;
+    return `US$${cachedFormatter({ maximumFractionDigits: 0 }).format(value)}M`;
   }
   if (fmt === "currency_aud_bn") {
     return `A$${value.toFixed(1)}B`;
   }
   if (fmt === "currency_aud_m") {
-    return `A$${value.toLocaleString(LOCALE, { maximumFractionDigits: 0 })}M`;
+    return `A$${cachedFormatter({ maximumFractionDigits: 0 }).format(value)}M`;
   }
   if (fmt === "usd") {
     return formatCurrency(value, "USD", 2);
@@ -100,10 +112,10 @@ export function formatChartKitNumber(value: number, fmt?: ChartKitFmt): string {
 
   const numDecimals = parseDecimals(fmt, "num");
   if (numDecimals !== null) {
-    return value.toLocaleString(LOCALE, {
+    return cachedFormatter({
       minimumFractionDigits: numDecimals,
       maximumFractionDigits: numDecimals,
-    });
+    }).format(value);
   }
 
   const audDecimals = parseDecimals(fmt, "aud");
@@ -120,10 +132,10 @@ export function formatChartKitNumber(value: number, fmt?: ChartKitFmt): string {
   if (currencyThousandsToken) {
     const symbol = currencyThousandsToken.currency === "AUD" ? "A$" : "US$";
     const scaled = value / 1_000;
-    return `${symbol}${scaled.toLocaleString(LOCALE, {
+    return `${symbol}${cachedFormatter({
       minimumFractionDigits: currencyThousandsToken.decimals,
       maximumFractionDigits: currencyThousandsToken.decimals,
-    })}K`;
+    }).format(scaled)}K`;
   }
 
   const currencyToken = parseCurrencyToken(fmt);
@@ -131,7 +143,7 @@ export function formatChartKitNumber(value: number, fmt?: ChartKitFmt): string {
     return formatCurrency(value, currencyToken.currency, currencyToken.decimals);
   }
 
-  return value.toLocaleString(LOCALE);
+  return cachedFormatter({}).format(value);
 }
 
 export function formatChartKitDisplayValue(value: unknown, fmt?: ChartKitFmt): string {
diff --git a/chartkit/src/lib/runtime/db-manager.ts b/chartkit/src/lib/runtime/db-manager.ts
index d9cc521..1f1eb0f 100644
--- a/chartkit/src/lib/runtime/db-manager.ts
+++ b/chartkit/src/lib/runtime/db-manager.ts
@@ -44,12 +44,12 @@ export async function getSharedRuntime(
     return runtime;
   }
 
+  // createDuckDbRuntime already calls registerDataSources with the initial
+  // dataSources array, so we skip the redundant second call for new runtimes.
   const runtimePromise = createDuckDbRuntime(dataSources, onTelemetry, options).catch((error) => {
     runtimeByKey.delete(key);
     throw error;
   });
   runtimeByKey.set(key, runtimePromise);
-  const runtime = await runtimePromise;
-  await runtime.registerDataSources(dataSources);
-  return runtime;
+  return runtimePromise;
 }