It seems that you set the dbcache more than your current RAM memory size since you have 8GB of memory you shouldn't set it to more than 4096MB.

I suggest try to change it to 4096 but before you do that make sure to stop the syncing process first if you are using a GUI just exit the GUI, and it will shut down automatically if not you can use "bitcoin-cli stop" to avoid corruption reboot your PC and rerun everything then monitor it again if the syncing process still slow or not.