how many content type fields can I have on a drupal site?
In Views, take a look at the SQL that it is generating in the preview of the view.  If you see tons and tons of JOINs, one for each field, that is most probably the cause of the slowdown.  What Drupal does is create a table for each field that is shared between content types and that means Views has to join everything back together again based upon the nid.  So, if this is happening, you might be able to improve performance by having each of these fields unique to an individual content type.  In that case, just as long as they are single value fields, they will just be another column in the database table defining the content type and can be grabbed all at once.