Hi, sorry we didn't respond sooner. Truth of the matter, this isn't what most users are experiencing. OmniWeb 5.6 (and 5.7 beta) are based off of the same rendering engine that Safari uses and should be comparable in performance.
It might be helpful to know which page you're trying to load (even if it is all pages having a specific example can be useful). If you could also try setting aside your disk cache located here:
And your history index here:
And let us know if that helps. Be sure to remove these while OmniWeb is not running.
If you continue to see poor performance grabbing a sample may help. To do this, open Activity Monitor found in the Applications > Utilities folder. Double click OmniWeb in the list and in the new window that appears, click on the Sample button. Save the sample that appears to disk and attach it here or send it to our support address at firstname.lastname@example.org
and we'll get back to you as soon as possible.
Again, sorry we didn't respond to you sooner and sorry you're having trouble with OmniWeb.