farm-recheck is the time (in milliseconds) interval your miner checks the farm for new work/block changes.
You will punish your farm, but, get new work sooner after a block change.

Won't make a world of difference, but, it will help a little.

Notes:
If you use a stratum proxy, a lower farm-recheck is fine as your actually just punishing your proxy.
The proxy "subscribes" to block changes.

Genoil's hard work implementing stratum should make the farm-recheck a thing of the past with stratum-capable pools.