By now, you should be able to see a window showing a color-coded breakdown of how you're using your MacBook's hard drive. After this, go to 'About this Mac' and click on 'Storage'. Go to the 'Apple' icon in macOS and click it. So, if you've noticed a dip in performance, there's a relatively simple way to check if this might be the cause (or at least a contributing factor).
Having less than 20% free hard drive space on your Mac can have an impact on how it functions. We go into this in more detail, of course, plus some things you can do yourself to help your MacBook run more smoothly. This is precisely where a MacBook Cleaner, like ours, can come in handy. If you're using a type of MacBook with macOS, there's a chance it could slow down if you've had it for a couple of years or more due to it collecting multiple apps, associated files, background processes, and system junk.