Pascal, Pascal, my first true love

I stopped using it when Borland tools lost favor to Microsoft, and C+ (and C++) got OOPs.
True, RegEx is fairly CPU intensive. Most of the client/server stuff I've done runs fine using RegEx, but they have been 100 concurrent users or less. So we are talking another order of magnitude. Personally, you are right on about building it as client-side parsing and server side validation; and also correct in that there may be little bang for the buck considering some of the other additions/optimizations that could be done.
I'm delving back into the Unix/Linux world after a few years absence. Going to set up a Mac, Ubuntu, and Commodore 64 (yes, you read it right) for a Networking course I'm teaching to show the students all sorts of computers can run on the exact same network.
One of the hardest things with the IT profession is that you could easily spend 40 hours a week just reading about all the new technology and not getting any real work done. Thus, we are forced to silo ourselves and resist the temptation to experiment with "cool" new things. I'm lucky as a professor, as part of my job is to examine new theory and literature. Some of my more interesting recent finds are Ant Theory for optimizing high-speed networks and data infrastructures, Digital Tattoos using either filaments or nanobots injected under the skin, and ink jet technologies allowing one to use specialized ink cartridges to 'print' batteries, circuit boards, display screen, and even human tissue.