Use ctrl-r a lot (navigate up/down with ctrl-p and ctrl-n) and try to “fuzzy-match” previously used commands. There is a very useful command called fzf which, while only a search program at heart, can be configured to complement this nicely.

Under about:unloads, you will see a list of open tabs, sorted by resource usage. You can click-spam the “Unload” button until that list is empty, or until the most resource-intensive tabs are off the list.

This does not require any third-party dependencies, and the tab will still be present on top. The site will reload once the tab is selected again.