recordid's filename grammar compiles a fresh regexp on every call: idRe (behind FilenameNumRe) runs regexp.MustCompile each time, and both per-file readers call it once per record file, the resolver's fileID in internal/core/recordid/resolve.go and peers' fileID in internal/core/peers/read.go. Every resolver scan and every peers scan, which the bare board runs on each render, therefore recompiles the same pattern once per record in the checkout: 29% of the CPU of the bare-board tests in internal/surface/cli, and several times that under -race, where it inflates the macOS check leg that iss-2609261924541555 records running past the merge queue's cap. The grammar is a pure function of a fixed family prefix, so one compiled pattern per prefix answers identically.

recordid's filename grammar compiles a fresh regexp on every call: idRe (behind FilenameNumRe) runs regexp.MustCompile each time, and both per-file readers call it once per record file, the resolver's fileID in internal/core/recordid/resolve.go and peers' fileID in internal/core/peers/read.go. Every resolver scan and every peers scan, which the bare board runs on each render, therefore recompiles the same pattern once per record in the checkout: 29% of the CPU of the bare-board tests in internal/surface/cli, and several times that under -race, where it inflates the macOS check leg that iss-2609261924541555 records running past the merge queue's cap. The grammar is a pure function of a fixed family prefix, so one compiled pattern per prefix answers identically.

Grounds

• pursued: every resolver and peers scan reads the grammar once per record file without compiling it; FilenameNumRe returning a distinct pattern per call, or fileID allocating more than 8 times per id, would show it wrong.