The new genericized LRU cache no longer needs to have the IDs separately
allocated:
name old time/op new time/op delta
Add-8 494ns ± 2% 388ns ± 2% -21.46% (p=0.000 n=10+9)
name old alloc/op new alloc/op delta
Add-8 176B ± 0% 152B ± 0% -13.64% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
Add-8 5.00 ± 0% 3.00 ± 0% -40.00% (p=0.000 n=10+10)
restic dump uses bloblru.Cache to keep buffers alive, but also reuses
evicted buffers. That means large buffers may be used to store small
blobs, causing the cache to think it's using less memory than it
actually does.
