Use slice instead of list, no map

benchmark                           old ns/op     new ns/op     delta
BenchmarkJobQueueBump               345           154498        +44682.03%
BenchmarkJobQueuePushPopDone10k     9437373       3258204       -65.48%

benchmark                           old allocs     new allocs     delta
BenchmarkJobQueueBump               0              0              +0.00%
BenchmarkJobQueuePushPopDone10k     10565          22             -99.79%

benchmark                           old bytes     new bytes     delta
BenchmarkJobQueueBump               0             0             +0.00%
BenchmarkJobQueuePushPopDone10k     1452498       385869        -73.43%
Only buffer file names, not full &FileInfo
wip
Refactor / cleanup