OP wrote:
"I found myself in this situation several times now, when I would be browsing something or looking for information and upon opening a particular site, my computer gets pesky ads and then my screen and cursor freeze."
If these are "known dodgy" sites, well... don't go to them.
Otherwise, I'll offer a trick that I use when encountering a website that is literally "filled up with crapola".
TURN OFF javascript and just reload the page.
Now... you can see "the text" of the page without all the crud that would need javascript to run.
There are components of the page you won't see after doing this, such as popups, videos, slideshows, etc.
But you'll still be able to read the basic text of the page (and most times, that's all I really wanted to see anyway).
You need to open Safari's preferences.
Go to the "advanced" pane.
Put a check into "show develop menu in menu bar" (at the bottom).
Now (when a page is filled with "crapola"), just go to the "Develop" menu and choose "disable javascript".
Next, type "command-R" to RELOAD the page WITHOUT javascript running.
I used the keyboard pref pane to set up an application key command for Safari -- "command-J" -- that toggles javascript on and off.
So now, I just hit "command-J" and then "command-R" to reload a page without javascript in less than a second.
By the way, this also works with all those "news sites" that would otherwise force you to "subscribe" to them.
Get rid of javascript, and you can still see the articles.
Give this a try.
I predict that it will solve many of the problems you're having.