Latency Issues During Load (especially Uploading)

Owned modem: CM1000v2

Plan: 1,200 / 40

I've tried every possible combination. The following result is with me directly connect to modem straight from point of entry removing any splits between.... I get high latency issues the second my modem is put under any kind of load. I even have a hard time playing simple games on Xbox Live without latency spikes and lagging.

I get "good" download and upload speedtest results but my problem is the latency spike when under load.  Even with 900mbs down I get a grade "C" from Bufferboad/Waveform and here is the Ookla test that shows my large increase in both download and upload latency (again plugged directly into modem without any splitters along the way):