Thanks for the feedback. I'm curious roughly how many bookmarks you have? If you have an extremely large bookmarks database (as in hundreds of thousands or millions of bookmarks), it's possible this may have an impact on Tab Stash memory usage. However, it's hard to say without more details.

I'd love to help further, please feel free to open an issue on GitHub: https://github.com/josh-berry/tab-stash/issues/new/choose