Metbase cant load my tables

i know that the connection to the database is ok and i was working with metabase for a month but today when i wanted to see one of my dashboards metabase tooke so much time on loading and it cant load anything, it tells me :
''Still Waiting…

This usually takes an average of 0 seconds.
(This is a bit long for a dashboard)''
how can i fix this ? i was ok even two hours ago but now everything is helled!

Did you perform some kind of update? Or where there any changes that you are aware off?