There are several reasons: 1. The latest core may not be the best one regarding stability and compatibility. For example,  the core after 109 removed the support for win7. We want Maxthon works well for all current users. We will not update until we have a solution for such a case. 2. We don't have enough developers. It's not a simple copy/paste job to update the core since we must make sure all Maxthon extra features work well with the new core. It takes a lot of jobs to do a core upd