Performance and resource budgets

Zrimo keeps work close to the visible viewport. Page documents render a small window of pages and spreadsheets render a canvas-sized cell range instead of a full sheet. Format engines, workers and optional font packs are loaded only when the opened document requires them.

Actual first-render time depends on document structure, compressed size, embedded media, selected fonts, device performance and browser canvas/WASM implementations. Applications with a strict latency target should benchmark representative documents on their own device matrix.

Rendering and memory controls

• Visible renders outrank adjacent pages, which outrank thumbnails. Only two render jobs run concurrently by default; queued stale work is aborted.
• Page DOM is virtualized with configurable overscan. PDF raster cache, decoded pixels, text-map bytes and document unit counts have hard limits.
• Every built-in worker operation has a 30-second default budget. Timeout returns resource-limit and terminates the worker/WASM heap.
• PDF cache evicts least-recently-used bitmaps before accepting a page that would cross its pixel budget. Close/destroy clears caches, listeners, object URLs and workers.

Applications can lower or explicitly raise limits through ViewerClient.create({ limits }). Raising them increases peak-memory and denial-of-service exposure; it should be based on a host-specific benchmark.

Delivery size

The npm package contains all supported format modules and optional fallback fonts, but a normal document does not download all of them. Configure assetBaseUrl so workers, the required WASM adapter and only the encountered script-specific font packs can be fetched independently and cached by the browser.

Avoid copying runtime assets into JavaScript bundles or importing every worker eagerly. The provided zrimo-copy-assets command preserves the directory layout expected by the lazy loader.

Integration guidance

• Keep the viewer container size stable while a document is open; repeated layout changes can invalidate visible canvases.
• Call destroy() when unmounting so workers, object URLs, canvases and caches are released promptly.
• Lower limits for untrusted public uploads and raise them only after measuring memory use on the weakest supported device.
• Serve .wasm, .mjs and font files with correct MIME types and long-lived, versioned cache headers.