I've seen the same behavior. Now trying to reset the router back to factory defaults. Only seemed to just now start happening the last week or two, and is incredibly frustrating. Ping times should not be measured in the seconds

.
Here is just a simple ping example. Without the router, I'm in the high teens consistently.
Pinging
www.google.com [64.233.176.105] with 32 bytes of data:
Reply from 64.233.176.105: bytes=32 time=984ms TTL=43
Reply from 64.233.176.105: bytes=32 time=33ms TTL=43
Reply from 64.233.176.105: bytes=32 time=477ms TTL=43
Reply from 64.233.176.105: bytes=32 time=225ms TTL=43
Reply from 64.233.176.105: bytes=32 time=489ms TTL=43
Reply from 64.233.176.105: bytes=32 time=33ms TTL=43
Reply from 64.233.176.105: bytes=32 time=28ms TTL=43
Reply from 64.233.176.105: bytes=32 time=487ms TTL=43
Reply from 64.233.176.105: bytes=32 time=37ms TTL=43
Reply from 64.233.176.105: bytes=32 time=1162ms TTL=43
Reply from 64.233.176.105: bytes=32 time=36ms TTL=43
Reply from 64.233.176.105: bytes=32 time=250ms TTL=43