I have a problem with YouTube on Chrome on my MacBook Air. If I start YouTube the CPU goes to about 100% immediately. If I kill the YouTube (YT) tab the CPU stays at 100% for about 15 - 16 minutes then drops off to almost nothing. Activity Monitor shows me that it is the main Google Chrome process itself (not helper or renderer) using all the CPU and it has the Google icon next to it. I am running Mojave 10.14.3. This is a relatively new problem for me. I do not have this issue when I run YT on Safari.