this is the first time I noticed this (which does not mean it was there in pre-4 releases, though at least there, I didn't notice it):
When LS is engaged, it slows down reading from the NAS on my LAN (a Synology DiskStation DS-716+) significantly.
LS Network Filter off: ~70 MB/s (large data reads)
LS Network Filter on: ~40 MB/s (large data reads)
This was immediately visible in LS's own Network Monitor throughput readings, and could reproducibly be traced back to the Network filter being off (fast) to on (slow, about 40% speed decrease).
I have about 1400 rules. I added a rule unconditionally allowing all LAN traffic, with code signature not being checked. (A similar rule came with LS, albeit with code signature checking on. Do these interfere with each other?)
1. Is this slowdown expected behaviour?
2. If so, is there a way to make (at least) LAN traffic faster somehow by adding/modifying/relaxing/disabling certain rules?
I am running OS X 10.11.6 on a Mac Pro (Early 2009) on GBit Ethernet in my LAN and fixed IPs for all devices. The protocol used between the NAS and the Mac is SMB.
I am using the NAS for backing up my Mac, so good performance is key. Yet I would not want to uninstall LS for the safeguarding it provides against the software that I am running, which may contact the outer world.