With this is mind I have changed the default settings so that only 20 topics are shown per page, and only 20 posts per page within each topic. Pages will load faster but you'll have to navigate through multiple pages in the larger forums.
For the benefit of members on faster connections I have added a modification to the control panel which allows you to adjust these settings individually. If you click the 'User Control Panel' link above, then click on the 'Profile' tab you'll now see two new options. You can change these settings to anything up to 250 - for example, I've set mine to 100 on each.
Have a play about and get the forum looking right for you