i have more than 6000 usergroup in my joomla
Why? That is a complete abuse of the ACL system. It is not designed to scale like that. You should ideally never have more than 30ish usergroups. Joomla's ACL is slow and having that many will make your entire site slower on every single page since ACL is ran on every single page. It's also going to make permissions pages basically unusable.
is there anyway to increase load speed page?
Yes, have less usergroups. We're not going to implement optimizations for scenarios that should not exist.