doc: add perf benchmark (#498)

* doc: add perf benchmark

* update

Author: ymc9

versioned_docs/version-3.x/orm/benchmark.md

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+---
+sidebar_position: 18
+description: ORM performance benchmark
+---
+
+# Performance Benchmark
+
+## Overview
+
+ZenStack maintains a fork of [prisma/orm-benchmarks](https://github.com/prisma/orm-benchmarks) and included ZenStack v3 into the test matrix. This page will be periodically updated with the latest benchmark results.
+
+Please understand ORM performance is a complex topic because different applications may have very different database configurations, data patterns and query profiles. The benchmark results should be used to understand if things are **in the right ballpark**, rather than exact performance numbers you will get in your application.
+
+### Repository
+
+[zenstackhq/orm-benchmarks](https://github.com/zenstackhq/orm-benchmarks)
+
+### Configuration Notes
+
+The Prisma tests are run with the new (Rust-free) [prisma-client](https://www.prisma.io/docs/orm/prisma-schema/overview/generators) generator and with the [relationJoins](https://www.prisma.io/docs/orm/prisma-client/queries/relation-queries#relation-load-strategies-preview) preview feature. We believe this aligns better with how the majority of users will use Prisma going forward.
+
+### How to Read the Results
+
+The numbers shown are in milliseconds per operation; lower is better. ZenStack's numbers are used as a baseline and compared against other ORMs. The percentage numbers in parentheses show how much faster (negative) or slower (positive) the other ORMs are compared to ZenStack.
+
+## Results
+
+### Local PostgreSQL
+
+> Tests are run against a PostgreSQL database in a local Docker container.
+
+Iteration count: 100  
+Dataset size: 500
+
+|ORM|findMany|findMany-filter-paginate-order|findMany-1-level-nesting|findFirst|findFirst-1-level-nesting|findUnique|findUnique-1-level-nesting|create|nested-create|update|nested-update|upsert|nested-upsert|delete|
+|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+|zenstack|3.62|1.23|118.28|1.08|1.10|0.64|0.95|2.10|4.48|1.70|2.64|1.42|2.53|2.02|
+|prisma|3.04 (-15.95%)|1.35 (+9.86%)|134.43 (+13.66%)|1.37 (+26.98%)|1.53 (+39.37%)|0.97 (+52.42%)|1.53 (+61.20%)|1.84 (-12.67%)|4.98 (+11.30%)|1.22 (-27.88%)|3.10 (+17.41%)|2.70 (+90.26%)|2.74 (+8.18%)|1.53 (-24.27%)|
+|drizzle|8.42 (+132.62%)|0.97 (-21.18%)|94.88 (-19.78%)|1.09 (+1.39%)|1.15 (+4.82%)|0.74 (+15.88%)|1.15 (+21.70%)|1.61 (-23.57%)|3.72 (-16.84%)|0.88 (-47.98%)|2.25 (-14.80%)|0.77 (-45.54%)|2.08 (-17.96%)|1.28 (-36.74%)|
+|typeorm|1.73 (-52.10%)|0.73 (-40.98%)|23.24 (-80.35%)|0.87 (-19.29%)|1.30 (+18.26%)|0.37 (-42.66%)|1.06 (+11.64%)|1.80 (-14.13%)|2.80 (-37.41%)|0.51 (-69.89%)|1.41 (-46.69%)|1.60 (+12.60%)|2.02 (-20.07%)|0.91 (-54.96%)|
+
+### Remote PostgreSQL
+
+> Tests are run from a local machine against a PostgreSQL database from [Neon](https://neon.com/) in the us-east-1 region.
+
+Iteration count: 20  
+Dataset size: 500
+
+|ORM|findMany|findMany-filter-paginate-order|findMany-1-level-nesting|findFirst|findFirst-1-level-nesting|findUnique|findUnique-1-level-nesting|create|nested-create|update|nested-update|upsert|nested-upsert|delete|
+|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+|zenstack|266.88|89.09|379.77|83.93|89.51|87.56|89.48|261.96|719.56|257.24|438.89|264.01|430.05|256.50|
+|prisma|349.80 (+31.07%)|173.51 (+94.76%)|485.73 (+27.90%)|171.33 (+104.15%)|179.38 (+100.41%)|173.32 (+97.95%)|180.36 (+101.57%)|175.17 (-33.13%)|1043.86 (+45.07%)|174.61 (-32.12%)|681.50 (+55.28%)|613.88 (+132.52%)|603.02 (+40.22%)|178.72 (-30.32%)|
+|drizzle|1067.94 (+300.16%)|177.13 (+98.83%)|284.89 (-24.98%)|174.92 (+108.42%)|178.58 (+99.51%)|176.94 (+102.08%)|180.89 (+102.16%)|183.68 (-29.88%)|716.85 (-0.38%)|179.00 (-30.42%)|532.09 (+21.24%)|176.24 (-33.25%)|540.86 (+25.77%)|180.24 (-29.73%)|
+|typeorm|268.19 (+0.49%)|87.74 (-1.51%)|473.78 (+24.76%)|86.04 (+2.52%)|182.50 (+103.90%)|88.06 (+0.57%)|175.96 (+96.66%)|265.91 (+1.51%)|436.68 (-39.31%)|88.39 (-65.64%)|348.48 (-20.60%)|355.76 (+34.75%)|443.17 (+3.05%)|88.53 (-65.48%)|
+
+## Observations
+
+### Cold Start Overhead
+
+While not readily observable in the numbers, ZenStack has a higher cold start overhead due to the usage of [Zod](https://zod.dev/) for input validation. Zod does JIT compilation of schemas on the first run. This overhead is amortized over multiple operations. The worst-case cold start overhead observed is around 20ms in the test environment.
+  
+### Why Is ZenStack Slower for Simple Mutations?
+
+Right now, ZenStack wraps every mutation in an explicit transaction. Although it doesn't make a real difference on the database side because PostgreSQL will do it anyway behind the scenes, it adds communication overhead between the client and the database server.
+
+There'll be optimizations for this in the future.