This is not normal.
Determine what Safari Extensions may be the cause. Go to the Safari menu > Preferences > Extensions. If you see any extensions that you do not recognize or understand, simply click the Uninstall button and they will be gone.
Also read the following:
If after considering the above the problems still exist, reply for more troubleshooting suggestions.
Something's amiss if Safari is actually 10GB's of memory. The issue may be extensions and third party pugins, not just the Safari app itself.
From your Safari menu bar click Safari > Preferences then select the Extensions tab. Turn that OFf.
Now select the Security tab. Deselect: Allow all other plug-ins
Quit and relaunch Safari to test.