Increased bundle size after upgrading AI SDK to v5

cipherohit · September 22, 2025, 8:24am

Is anyone else also facing the problem of increasing bundle size after upgrading vercel AI SDK to v5?

anshumanb · October 3, 2025, 4:45am

Hi @cipherohit, welcome to the Vercel Community!

Can you share some before and after measurements of your bundle size? There’s a minimal change in the size:

ai@v5:
ai v5.0.59 ❘ Bundlephobia - 67.5kB
ai@v4
ai v4.3.19 ❘ Bundlephobia - 53.8kB

Looking forward to hearing from you.

pawlean · October 10, 2025, 3:09pm

In case this is helpful:

github.com/vercel/ai

CI: add bundle size and benchmark monitoring

opened 03:30PM - 08 Oct 25 UTC

gr2m

maintenance

We received reports of slow import/instantiation times for AI SDK - https://git…hub.com/cloudflare/workers-sdk/issues/10723 - https://dev.to/dzakh/zod-v4-17x-slower-and-why-you-should-care-1m1 - https://x.com/hichaelmart/status/1975328481669226946 We are looking into mitigating the problem. One thing that we decided is needed is to make bundle size and benchmark monitoring part of our CI Some relevant insights by @colinhacks - https://github.com/colinhacks/zod/issues/4637#issuecomment-2950064668 ### Related - https://github.com/vercel/ai/pull/9275 - https://github.com/vercel/ai/pull/9285

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Increased bundle size after upgrading AI SDK to v5

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