13-CURRENT: several GB swap being used despite plenty of free RAM

[Rebecca Cran]

I'm running 13-CURRENT from a few days ago. I noticed the system using several 
GB of swap despite having 90GB RAM still free. I know FreeBSD will use *some*, 
but 3450MB seems excessive when there's still 90GB RAM free.

CPU:  0.1% user,  0.0% nice,  0.0% system,  0.0% interrupt, 99.8% idle
Mem: 3392M Active, 5489M Inact, 390M Laundry, 25G Wired, 90G Free
ARC: 19G Total, 8080M MFU, 9242M MRU, 64K Anon, 197M Header, 1570M Other
     15G Compressed, 26G Uncompressed, 1.73:1 Ratio
Swap: 8192M Total, 3450M Used, 4742M Free, 42% Inuse, 36K In

Quitting firefox caused the swap usage to drop to just 460MB. I don't 
understand why it would decide to swap out so much, especially since I have 
vm.swap_idle_enabled set to 0.

-- 
Rebecca