It takes a lot more than your internet to synchronize your wallet. The common issue is with the CPU. Try opening your task manager and see if the usage is rising as the download stops.
Else, if you increase your dbcache, it would certainly help you with the synchonizing significantly.
What dbcache value should I be using and what does this dbcache value is choosen in respect to? like depending on how much RAM you got, or CPU power?
I've got 8 gigs of RAM, I got a pretty old CPU tho, it's a 2008 quadcore, but still serves me well in most tasks. Modern CPU's have the Intel Management spywarefest so I never bothered updating.
I will try to monitor later the CPU cycles and see if they go during these gaps, probably could be that it's processing the blocks and can't download and process at the same time??