So I too have noticed a significant improvment in how long it takes to ping. and the funny thing is... i have not updated my phone yet (still waiting) im currently getting readings as follows:
WIFI
11.56 mbps download,
11.96 mbps upload,
71 ms ping,
NETWORK 4G:
6.56 mbps download,
1.53 mbps upload,
86 ms ping.
I ran it twice for each at different times and all results were similar, which is crazy because just two weeks ago i was in the 1000s. so T-mobile must have done something, and it obviously wasnt the update