1. when you have 99% usage, it will take a long time for the task manager to open. You'll have to be patient.
2. your screenshot looks generally ok (although there are some processes you can probably live without - check the startups) , but it does not show all the processes (you'll have to enlarge the window a little - pull it down). And click on (working set(memory)). Then it will show the big RAM eaters on top.