uBlock Origin usually rather decreases RAM usage, since ads tend to take up a fair chunk of RAM, too. If you want to troubleshoot it, type "about:memory" into

uBlock Origin usually rather decreases RAM usage, since ads tend to take up a fair chunk of RAM, too. If you want to troubleshoot it, type "about:memory" into the URL-bar and hit enter, then click the "Measure"-button to the left. This should give you a pretty detailed listing of everything that takes up RAM, and usually, high RAM usage is caused by an extension having memory leaks, so you'll probably see a pretty big number somewhere near the root of the tree and should be able to follow it along to whatever is causing it. If it is an extension, obviously try to find a replacement, if it's not an extension, you should probably file a bug report...