By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Mutation: skip the GRE lookup in headNameMatches when no names configured The ignore filter runs headNameMatches on every expression in every instrumented module. With a non-empty name list it peels the head and looks the name up in the GlobalRdrEnv; with an empty list (the common case — no `ignore` configured) that work is wasted, since the candidates are matched against `[]`. Short-circuit the empty-list case so the default config pays nothing per expression. Behaviour is unchanged (`any (`elem` []) ...` was already False).
| Time to Start | Worker time | Duration | Time to finish | Idle | |
| Config | 0s | 2s | 2s | 2s | 0s |
| Eval | 1s | 38s | 38s | 40s | 0s |
| Build | 5s | 44s | 22s | 27s | 0s |
| Suite | 0s | 1m24s | 40s | 40s | 0s |