There's a ton of lag in Photoshop Elements 13 on my computer. Does anyone know how to

Elements should work fine with an i5 computer. The hang up might be the amount of available RAM and the amount of free space on the hard drive that Elements can use as a scratch disk. Let me 'splain:-) Elements (and most other photo and video editors) can undo the steps you take when you edit something. They can undo because all the steps are saved to a scratch disk that's a temporary space on the hard drive that exists only when you edit. The information saved to the scratch disk is retrieved as you work on a project and moves via the RAM back and forth from the program to the scratch disk.

There are ways to make Elements more efficient. Go to Edit>Preferences>Performance. There are two things to look at: amount of RAM allocated to the program and the scratch disk. I usually give Elements 65% of the available RAM. This has always worked for me because I don't have a lot of things running in the background when I edit photos and videos. I'm not streaming music, running anti-virus scans, etc. While I work with Elements.

About the Scratch Disk. If you've got more than one hard drive, you can tell Elements which one to use. Since our computers usually have 500GB or larger hard drives, I try to keep about 1/2 of the total GBs free so the programs I use have plenty of space. The more used GBs on your hard drive the slower retrieving information from that drive is going to be. If you've got a 500 GB hard drive and still have 150 GB free, even though 150 GBs sounds like a lot, getting information onto and off of that drive is going to be slower than if 250 GBs of the drive were unused and free.