Tracking down a performance issue. Linux server will sometimes show extremely high load, but little cpu utilization and practically no disk wait

I've been trying to track down a performance issue on a linux server where occasionally the load will spike to something like 80-120. It slowly grows when this situation happens and I notice virtual memory for some processes seems to steadily climb as well. What could I check to try and track down what is causing this performance issue/heavy load on the box?

htop will generally show very little cpu usage but the load will be extremely high and practically no wait.

Thanks