Comment 158 for bug 1518457

Zswap isn't to blame, dropping caches may help or may not. There's the output of `sudo perf top`:

  26,24% [kernel] [k] _raw_spin_lock
  14,72% [kernel] [k] _raw_spin_unlock
   6,62% [kernel] [k] super_cache_count
   4,97% [kernel] [k] shrink_slab.part.12
   4,92% [kernel] [k] list_lru_count_one
   2,15% [i2c_designware_core] [k] 0x0000000000000099
   1,86% [kernel] [k] shrink_lruvec
   1,74% [kernel] [k] mem_cgroup_iter
   1,61% [kernel] [k] native_read_tsc
   1,55% [kernel] [k] delay_tsc
   1,52% [kernel] [k] kswapd%