Server grinds to a halt when I use custom URL rewrite settings?

I have to date been using the default vBSEO setup for URL settings. I try to change a few of them, so I can use 'smart stopwords' (I really need them) and to customise my URL's to folders, but every page of the site grinds to a halt and (eventually) loads a blank page. If I switch back to the default setup;

Current Preset: 001 - Hierarchic .html type URLs with content relevant forums and threads (Default Settings)

...Everything runs just fine, no slowdown in the slightest. I do not understand how implimenting a setting which should help with load brings everything to a stop.

Any input much appreciated.

Hello,

what do you change in your URL formats?

Just removing .html extension to make them folders, even if I do not change URL formats and change only 1 setting; e.g. limit URL length to 128 characters it all runs to a stop.

Hello,

please open a support ticket with ftp/vbseocp access for troubleshooting.

Ticket sent, thanks.