Performance degradation using `/chromium/pdf` REST API

Author: uh-zuhCreated May 21, 2026Updated Aug 26, 2026

Describe the bug There is performance degradation after 10-20 request to /chromium/pdf REST API. And performance becomes better after approx 1 minute of idle.

To Reproduce

Set ENABLE_CORS=true for reproduction purpose only
Run following code in any browser:

javascript

(async () => {
    let totalDiffMs = 0;
    const steps = 50;

    for (let i = 0; i < steps; i++) {
        const dateBegin = new Date();
        await fetch(
            'http://localhost:3000/chromium/pdf',
            {
                method: 'POST',
                headers: { 'Content-type': 'application/json' },
                body: JSON.stringify({ html: 'test' }),
            },
        );
        const dateEnd = new Date();
        const dateDiffMs = dateEnd.getTime() - dateBegin.getTime();
        totalDiffMs += dateDiffMs;
        console.log('i: ', i, ', dateDiffMs:', dateDiffMs);
    }

    console.log('avgDiffMs:', totalDiffMs / steps);
})();

See good performance with first 10-20 requests and performance degradation in console like this:

i:  0 , dateDiffMs: 335
i:  1 , dateDiffMs: 380
i:  2 , dateDiffMs: 483
i:  3 , dateDiffMs: 399
i:  4 , dateDiffMs: 383
i:  5 , dateDiffMs: 342
i:  6 , dateDiffMs: 357
i:  7 , dateDiffMs: 348
i:  8 , dateDiffMs: 334
i:  9 , dateDiffMs: 350
i:  10 , dateDiffMs: 353
i:  11 , dateDiffMs: 330
i:  12 , dateDiffMs: 343
i:  13 , dateDiffMs: 328
i:  14 , dateDiffMs: 344
i:  15 , dateDiffMs: 317
i:  16 , dateDiffMs: 351
i:  17 , dateDiffMs: 369
i:  18 , dateDiffMs: 531
i:  19 , dateDiffMs: 614
i:  20 , dateDiffMs: 616
i:  21 , dateDiffMs: 601
i:  22 , dateDiffMs: 615
i:  23 , dateDiffMs: 633
i:  24 , dateDiffMs: 573
i:  25 , dateDiffMs: 610
i:  26 , dateDiffMs: 601
i:  27 , dateDiffMs: 665
i:  28 , dateDiffMs: 591
i:  29 , dateDiffMs: 569
avgDiffMs: 455.5

Wait 1 minute
See good performance with first 10-20 requests and performance degradation again
Repeat 1-2 more times to see that such pattern is repeating

Expected behavior No performance degradation

Version v2.49.0

Source: browserless/browserless

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