pkg/util/encoding: potential performance regression

pkg/util/encoding [performance regression](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachprodMicrobenchmarkWeeklyWip/20958673?buildTab=log) on master @ [94a1e22436ad935d8c7f9524cb8fc0fd7b24faaa](https://github.com/cockroachdb/cockroach/commits/94a1e22436ad935d8c7f9524cb8fc0fd7b24faaa):

Performance regressions detected in package pkg/util

Comparison: v25.4.2 (2c80e22e) -> refs/heads/master (94a1e224)

Found 21 benchmark(s) with regressions ≥20%:

- [ ] [pkg/util/encoding→DecodeNonsortingUvarint-32 (sec/op): +51.32% (51.3%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=DecodeNonsortingUvarint-32&package=pkg/util/encoding)
- [ ] [pkg/util/log→ExpensiveLogEnabled-32 (sec/op): +27.10% (27.1%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ExpensiveLogEnabled-32&package=pkg/util/log)
- [ ] [pkg/util/hlc→TimestampIsEmpty/empty-32 (sec/op): +25.13% (25.1%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=TimestampIsEmpty/empty-32&package=pkg/util/hlc)
- [ ] [pkg/util/encoding→EncodeUint64-32 (sec/op): +23.36% (23.4%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=EncodeUint64-32&package=pkg/util/encoding)
- [ ] [pkg/util/quotapool→ConcurrentIntPool/workers=512,quota=513-32 (sec/op): +21.89% (21.9%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ConcurrentIntPool/workers=512,quota=513-32&package=pkg/util/quotapool)
- [ ] [pkg/util/quotapool→ConcurrentIntPool/workers=512,quota=511-32 (sec/op): +21.68% (21.7%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ConcurrentIntPool/workers=512,quota=511-32&package=pkg/util/quotapool)
- [ ] [pkg/util/syncutil→AdversarialAlloc/*syncutil.RWMutexMap-32 (sec/op): +21.59% (21.6%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=AdversarialAlloc/*syncutil.RWMutexMap-32&package=pkg/util/syncutil)
- [ ] [pkg/util/shuffle→ConcurrentShuffle/concurrency=8/size=8192-32 (sec/op): +20.86% (20.9%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ConcurrentShuffle/concurrency=8/size=8192-32&package=pkg/util/shuffle)
- [ ] [pkg/util→FastIntMap/10x10-4/map-sized-32 (allocs/op): +200.00% (200.0%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=FastIntMap/10x10-4/map-sized-32&package=pkg/util)
- [ ] [pkg/util→FastIntMap/32x15-10/map-sized-32 (allocs/op): +200.00% (200.0%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=FastIntMap/32x15-10/map-sized-32&package=pkg/util)
- [ ] [pkg/util→FastIntMap/1000x1000-500/map-sized-32 (allocs/op): +150.00% (150.0%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=FastIntMap/1000x1000-500/map-sized-32&package=pkg/util)
- [ ] [pkg/util→FastIntMap/100x100-50/map-sized-32 (allocs/op): +50.00% (50.0%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=FastIntMap/100x100-50/map-sized-32&package=pkg/util)
- [ ] [pkg/util→FastIntMap/100x100-50/fastintmap-32 (allocs/op): +33.33% (33.3%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=FastIntMap/100x100-50/fastintmap-32&package=pkg/util)
- [ ] [pkg/util/parquet→ParquetWriter/regrole-32 (B/op): +58.40% (58.4%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/regrole-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/int4-32 (B/op): +53.63% (53.6%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/int4-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/regclass-32 (B/op): +53.41% (53.4%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/regclass-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/int2-32 (B/op): +53.30% (53.3%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/int2-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/int-32 (B/op): +42.25% (42.3%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/int-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/time-32 (B/op): +41.35% (41.3%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/time-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/pg_lsn-32 (B/op): +39.01% (39.0%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/pg_lsn-32&package=pkg/util/parquet)
- [ ] [pkg/util/parquet→ParquetWriter/int[]#01-32 (B/op): +25.60% (25.6%)](https://microbench.testeng.crdb.io/dashboard/?benchmark=ParquetWriter/int[]#01-32&package=pkg/util/parquet)
Help

See also: [How To Investigate a Go Test Failure \(internal\)](https://cockroachlabs.atlassian.net/l/c/HgfXfJgM)

Jira issue: CRDB-58601