43 is quite good.
The most important part of task manager is the total CPU usage. It should run at between 2 and 4%, with occasional high peaks when some task is working.
If yours is running higher, click on the processes tab, and double click on CPU, twice.
This will bring the processes that are using the most CPU to the top.
It is difficult to know what you can delete or stop working - very often they are not named properly but are essential to the running of the pc.
I assume you mean that some processes are running at 150k memory usage. My guess is that is your browser. If you restart your browser it should show a much lower usage.
What is the total CPU usage?