Hello Lewis, and thank you for choosing JustAnswer.com
YOu might be having a maxed out piece of hardware, that causes a slowdown of the Data stream.
Possibly the CPU, the RAM, or the hard drive is being pegged at 100% utilization.
This will cause the system to jump or hiccup constantly.
This can be caused by the HEAT in the system building up and causing overheating of the hardware.
But it could also be caused by failing hardware in general.
Its hard to say, at this point.
Can you look at your TASK MANAGER, and look at the performance tab.
Do you see any 95% - 100% spikes?