have previously rated this extension as good. since the latest update where tabs can now be kept open due to improved firefox functionality, i was not expecting too much - thought there may be problems, but instead it has worked flawlessly.
i have a close to 200 tabs open and everything seems to be working very well. there does not seem to be any slow down caused by memory consumption and switching between groups and going back and forth in some tabs have caused no problems.
have been using for about a week now and have gained confidence that it will continue to perform. a big thank you to morikko - well done!