Speed up Opencart and change price dynamically

I have worked with Opencart in the past. I just took a position with a large company and have convinced them to use Opencart. I have migrated a database of 6000+ products and thousands of customers. Running locally, it is somewhat slow. Are there any recommendations to speed it up with hardware or software, with money not being an issue?

Also, they have various customer groups who will get different pricing. In addition to this their pricing will change depending on the quantity they buy. There will need to be a way to override this on any specific product. Are there any modules that do this? Otherwise I will need to make one.

Answering the first question only - there have been a few threads about backend optimisation. Xsecrets and Qphoria have done most of the work with this. Some examples -
http://forum.opencart.com/viewtopic.php?f=20&t=34851
http://forum.opencart.com/viewtopic.php?t=23195
http://forum.opencart.com/viewtopic.php?f=121&t=22048
http://forum.opencart.com/viewtopic.php?f=24&t=24391
- a search should turn up more. Depends what your issue is and which version you're using.

There is also a thread on frontend optimisation
http://forum.opencart.com/viewtopic.php?f=23&t=8492

The largest OC installation I've heard of had 7 million products - the developer did plenty of custom work with it though.

Looks like there are some serious issues with the new version. I don't know why the category cache was disabled but I'll definitely need to find a way to bring it back.

There is a mod to speed up opencart which will improve page load speed massively.
With over 33,000 categories & 60,000+ products, page load time is fine.

http://www.opencart.com/index.php?route ... on_id=3444