Im currently using over 400 keywords for 1 ad group. Is that to many keywords for a ad group in your opinion and does that slow down your campaign? I have read where its best to just use 15 to 20 keywords per campaign. Im getting traffic, but it's coming mostly from the content network. I get about 60 to 100 clicks from the Search but in the beginning of my campaign i was getting over 200 clicks from Search alone.
I don't think having too many keywords in an ad group can directly affect number of clicks you are getting, but very large ad groups tend to be less focused and as a result keywords in such groups tent to have lower quality scores. And lower quality score leads to lower position and that will affect number of clicks.
For the content network, 400 in a group is too many and pointless - only 50 will be considered to establish the theme. For search, as far as I'm aware all keywords in the group will be considered, but you are putting yourself at a disadvantage by not splitting into smaller adgroups and targetting your ad text to your keywords with as much relevancy as possible.
No, we run 500 to ~750 all the time but updating it does cause slowness issues. Including hanging, session issues, etc. If you go to more powerful tools, this goes away. But you should always sort the keywords into groups that can be addressed by the Ads. Generic ad suck.