chore: speed up test suite slightly

[Garmelon]

This PR speeds up some benchmarks when run as tests by lowering their workload. It also stops testing some of the more expensive benchmarks that can't be easily made smaller.

[Garmelon]

!bench

[leanprover-radar]

Benchmark results for cefdd2b against 09da0d2 are in. There are no significant changes. @Garmelon

• ✅ build//instructions: -135.3M (-0.00%)

No significant changes detected.

[mathlib-lean-pr-testing]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 09da0d22a1861d5d10e4a446458e3a44526e0717 --onto 61a3443a9569d548a235f785b9a33984bb7ff622. You can force Mathlib CI using the force-mathlib-ci label. (2026-03-18 14:08:59)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 0f730662de0bbaa6ed07484d8f0e411de2bcd1ea --onto 61a3443a9569d548a235f785b9a33984bb7ff622. You can force Mathlib CI using the force-mathlib-ci label. (2026-03-19 18:03:13)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase c6a89cc71647554b34018e1ae579b20fa965f9b1 --onto 87180a09c49c91577e54284703c73c5ca76be126. You can force Mathlib CI using the force-mathlib-ci label. (2026-03-20 12:59:49)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 09da0d22a1861d5d10e4a446458e3a44526e0717 --onto cfa8c5a036d6990635c6ec50b02d0e806995cec3. You can force reference manual CI using the force-manual-ci label. (2026-03-18 14:09:00)
• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 0f730662de0bbaa6ed07484d8f0e411de2bcd1ea --onto cfa8c5a036d6990635c6ec50b02d0e806995cec3. You can force reference manual CI using the force-manual-ci label. (2026-03-19 18:03:15)
• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase c6a89cc71647554b34018e1ae579b20fa965f9b1 --onto cfa8c5a036d6990635c6ec50b02d0e806995cec3. You can force reference manual CI using the force-manual-ci label. (2026-03-20 12:59:51)

[Garmelon]

!bench

[leanprover-radar]

Benchmark results for 6dcf599 against 09da0d2 are in. Significant changes detected! @Garmelon

• 🟥 build//instructions: +310.4M (+0.00%)
• 🟥 other exited with code 2

No significant changes detected.

[Garmelon]

!bench

[leanprover-radar]

Benchmark results for ed803dd against 09da0d2 are in. There are no significant changes. @Garmelon

• ✅ build//instructions: -878.7M (-0.01%)

No significant changes detected.

[Garmelon]

!bench

[leanprover-radar]

Benchmark results for 3bb1903 against 0f73066 are in. Significant changes detected! @Garmelon

• ✅ build//instructions: -325.1M (-0.00%)
• 🟥 other exited with code 2

Small changes (1🟥)

• 🟥 build/module/Init.Data.Nat.ToString//instructions: +32.9M (+0.10%)

[Garmelon]

!bench

[leanprover-radar]

Benchmark results for de10a6a against c6a89cc are in. There are no significant changes. @Garmelon

• ✅ build//instructions: -59.8M (-0.00%)

Small changes (1🟥)

• 🟥 elab/charactersIn//instructions: +61.5M (+0.13%)

[Garmelon]

From my (unreliable, because I didn't reduce parallelism) measurements, this reduces the total time for *_bench tests from 680s to 410s.