WaveRT is not bad. Compared to the older drivers like MME/WDM, it's certainly much better in terms of latency. I've started from the era of using MME for DAW. I've used all the drivers. And ASIO still beats WaveRT. There's no competition. That's not to say in any way that WaveRT is not good. In my humble experience, it's just that ASIO is better. That's all.
However, if by some miracle it works for you (running so many simultaneous tracks), then stay with it. Still, I will recommend at least trying ASIOforall. Quite a number of people I know used internal soundcard with surprisingly good results - using ASIOforall. It's a free download. No harm trying.
Back to your original question on the need to optimize Windows off the shelf. Well, I don't use Windows 8 so I have no experience with it. But my suggestion is still to optimize. You can squeeze a lot more power with optimizing. You'll start to appreciate it when you start using lots of plugins. What I usually do (in this order):
1. Dual boot with dedicated boot partition for DAW.
2. Uninstall all useless drivers/devices (e.g. Smartcard reader, and in the case of using an external audio interface - disable the build-in soundcard; we already know you are not going that path

)
3. Uninstall all bloatware and useless Windows applications
4. Disable system restore, disable all eye-candy in Windows etc
5. Make sure Windows doesn't load useless stuff during startup - safest way is to use msconfig, but I would also use regedit to do deep registry cleaning manually (not recommended if you don't know what you are doing).
6. Many doesn't recommend this, but I would use a registry cleaner to clean out mess. JVPowertools is my standard - been using it since Windows 98 days without problems.
7. Defragment as the last step.
There are a few other tricks I would do. But the above ones are the key essentials.