I'm no network / data access guru, but this seems like a typical case of profile first, optimize later.
The idea is simple. Don't just go in and change stuff, first measure the pieces under typical load. Look where the bottle-neck is, address it, and move to the next bottle-neck. Repeat as often as needed.
Are you disk I/O bound? Buy faster disk / better controllers / spread the load over more machines / .....
Are you CPU bound? Is the CPU on your server spending so much time with I/O requests, that it has no cycles available to address additional requests? Buy more / faster / better CPUs.
Are you network bound? Which piece of the network is the hold-up? Your switch? Get a better / faster one. Your ISP? Get a fatter pipe.
Have you optimized all of these? What about setting up remote servers that are updated hourly/daily/weekly/whatever so the machine is close to the user network-wise for faster download speeds.
Some of the above adds complexity. Are you equipped to handle that complexity? Can you become equipped to handle it? If not, re-consider your options.
Hope this helps.