MacOS – Show When Applications Were Opened and Closed

I would not use Console.app. Instead use Terminal.app with the following command:

tail -f /var/log/system.log | grep "string you are looking for"

then leave that window open and you will see all matching entries in that window as you work.

Also know that when the system.log file is rotated (due to size/time) tail will stop. you will need to restart the command.

Your memory and CPU usage are normal. And you don't appear to have anything massive running.

Modern computers utilize as much memory as possible before swapping anything out to the (much slower) disk. If you have more than 1-2 programs open you should expect to see the memory mostly full. The OS will handle swapping / clearing it as needed.

My computer is getting old (almost 6 years old I think) and is becoming increasingly slow.

Computers do not slow down with age. But they do accumulate stuff. How full is your disk drive? If you have less than 20Gb or 15% free space your disk will take a lot longer to return results.

Or your disk is having issues. Either way, installing an SSD is a simple and cheap way to get a huge performance boost out of an older machine. The drives cost under $200 now, changing one takes 15 minutes but on a macbook Pro will require some special screwdrivers.