This is weird. It seems like the ping times with this new driver have reversed, but only for the first few minutes. I got consistently pretty bad ping times on my LAN , with occasional good ones. Pinging even my ASUS RT-AC66U router directly took a whopping 50 ms or so on average.
Reply from 192.168.0.1: bytes=32 time=99ms TTL=64
Reply from 192.168.0.1: bytes=32 time=4ms TTL=64
Reply from 192.168.0.1: bytes=32 time=84ms TTL=64
Reply from 192.168.0.1: bytes=32 time=78ms TTL=64
Reply from 192.168.0.1: bytes=32 time=76ms TTL=64
Reply from 192.168.0.1: bytes=32 time=67ms TTL=64
Reply from 192.168.0.1: bytes=32 time=67ms TTL=64
Reply from 192.168.0.1: bytes=32 time=68ms TTL=64
Reply from 192.168.0.1: bytes=32 time=63ms TTL=64
Reply from 192.168.0.1: bytes=32 time=61ms TTL=64
Reply from 192.168.0.1: bytes=32 time=63ms TTL=64
Reply from 192.168.0.1: bytes=32 time=58ms TTL=64
Reply from 192.168.0.1: bytes=32 time=56ms TTL=64
Reply from 192.168.0.1: bytes=32 time=47ms TTL=64
Reply from 192.168.0.1: bytes=32 time=56ms TTL=64
Reply from 192.168.0.1: bytes=32 time=52ms TTL=64
Reply from 192.168.0.1: bytes=32 time=51ms TTL=64
Reply from 192.168.0.1: bytes=32 time=64ms TTL=64
Reply from 192.168.0.1: bytes=32 time=34ms TTL=64
Reply from 192.168.0.1: bytes=32 time=27ms TTL=64
Reply from 192.168.0.1: bytes=32 time=16ms TTL=64
Reply from 192.168.0.1: bytes=32 time=9ms TTL=64
Reply from 192.168.0.1: bytes=32 time=9ms TTL=64
Reply from 192.168.0.1: bytes=32 time=102ms TTL=64
Reply from 192.168.0.1: bytes=32 time=100ms TTL=64
Reply from 192.168.0.1: bytes=32 time=91ms TTL=64
Reply from 192.168.0.1: bytes=32 time=85ms TTL=64
Reply from 192.168.0.1: bytes=32 time=84ms TTL=64
Reply from 192.168.0.1: bytes=32 time=78ms TTL=64
Reply from 192.168.0.1: bytes=32 time=75ms TTL=64
Reply from 192.168.0.1: bytes=32 time=74ms TTL=64
Reply from 192.168.0.1: bytes=32 time=68ms TTL=64
Reply from 192.168.0.1: bytes=32 time=66ms TTL=64
Reply from 192.168.0.1: bytes=32 time=50ms TTL=64
Reply from 192.168.0.1: bytes=32 time=42ms TTL=64
Reply from 192.168.0.1: bytes=32 time=38ms TTL=64
Reply from 192.168.0.1: bytes=32 time=26ms TTL=64
Reply from 192.168.0.1: bytes=32 time=19ms TTL=64
Reply from 192.168.0.1: bytes=32 time=59ms TTL=64
Reply from 192.168.0.1: bytes=32 time=3ms TTL=64
Reply from 192.168.0.1: bytes=32 time=99ms TTL=64
Reply from 192.168.0.1: bytes=32 time=106ms TTL=64
Reply from 192.168.0.1: bytes=32 time=100ms TTL=64
Reply from 192.168.0.1: bytes=32 time=101ms TTL=64
Reply from 192.168.0.1: bytes=32 time=95ms TTL=64
Reply from 192.168.0.1: bytes=32 time=87ms TTL=64
Reply from 192.168.0.1: bytes=32 time=81ms TTL=64
Reply from 192.168.0.1: bytes=32 time=82ms TTL=64
Fast forward a few minutes and now everything seems great! I still see the ping spikes with laggy TCP connections, but it seems like they are happening far less frequent. I have not observed any dropped connections, although it seems like that problem was solved with the BIOS/Firmware update I installed just a few days ago. I have not yet disabled uAPSD.
Reply from 192.168.0.2: bytes=32 time=1ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
Reply from 192.168.0.2: bytes=32 time=1ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
Reply from 192.168.0.2: bytes=32 time=1ms TTL=64
Reply from 192.168.0.2: bytes=32 time=180ms TTL=64
Reply from 192.168.0.2: bytes=32 time=76ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
Reply from 192.168.0.2: bytes=32 time=199ms TTL=64
Reply from 192.168.0.2: bytes=32 time=1ms TTL=64
Reply from 192.168.0.2: bytes=32 time=1ms TTL=64
Reply from 192.168.0.2: bytes=32 time=1ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
Reply from 192.168.0.2: bytes=32 time=2ms TTL=64
I will reboot now and see if these slow ping times happen every time for the first few minutes, or if it was just a fluke right after installing the new driver.