Slow parsing performance

I’ve just started using this library to check that parsed JSON objects conform to the types I define. I’m really enjoying it, but I’m afraid I’ve hit a performance snag.

Everything works fine with small tests but when I ran it on a slightly bigger input file (~10MB) I noticed that it was really slow.

I’ve tried the latest version and the beta, and check vs parse, with similar results. The beta is faster, but I don’t see a big difference between check and parse.

After profiling the check version in the beta, I’m seeing calls to .check taking in the 500ms-1100ms range per object.

Are those numbers typical, or am I doing something wrong with the schema definitions?

My schema definitions look like:

const EntryJsonSchema = z.object({
  a: z.string().optional().nullable(),
  b: z.string().optional().nullable(),
  id: z.string().optional().nullable(),
  creation: z.string().optional().nullable(),
  content: ContentJsonSchema.optional().nullable(),
  labels: z.string().array().optional().nullable(),
  answers: AnswerJsonSchema.array().optional().nullable(),
  results: ResultJsonSchema.array()
    .optional()
    .nullable(),
});

const ContentJsonSchema = z.object({
  id: z.string().optional().nullable(),
  title: z.string().optional().nullable(),
  version: z.union([z.number(), z.string()]).optional().nullable(),
});

const AnswerJsonSchema = z.object({
  key: z.string().optional().nullable(),
  value: z.any().optional().nullable(),
});

const ResultJsonSchema = z.object({
  key: z.string().optional().nullable(),
  value: z.any().optional().nullable(),
});

I’m really hoping that there is a way to speed it up, as this is too expensive for the use case where I’ll have to process files with 100k+ objects.

Thanks!

[joekrill]

This morning I decided to check in on zod and see if there’s been any changes (it’s been a few weeks since last I checked), and WOW! HUGE improvements since v3.1! Here is the results of my latest benchmark on our internal dataset adding Zod 3.5.1:

library	parse time (ms)
zod 3.5.1	76.74
zod 3.1.0	2453.06
zod 3.0.0	2080.56
zod 1.11.17	723.87
myzod 1.11.17	26.72

So just a massive improvement. This is so awesome. Thank you so much to @milankinen, @colinhacks, and everyone who has been contributing - I really appreciate you all. This is really amazing and definitely makes zod a usable option for me again - I’ll definitely be looking into switching back.

Side note: I did run into some minor tweaks I had to make to my schema where I was using passthrough with intersection which is causing an error in 3.5.1, but that was pretty straightforward to clear up.

[tmcw]

I’ve implemented #1023, #1021, and #1022 to explore different vectors at making zod faster. I think updating the target is the highest payoff for the least amount of change, but the other PRs also have some notable perf improvements. I’ll keep looking - I think it’s possible to make zod as fast as the alternatives.