USB Bootcamp affect performance?

[yusukeaoki]

I recently made a huge mistake to install my optibay before installing Bootcamp on my second drive.
Now I have everything set up, I dont want to go through the hassle putting it all back together.

Now on my old 500GB HDD, I still have my OS X 10.7.4 and Bootcamp.

If I use this bootcamp (which works fine) via USB, would this affect the performance?
For example, if I run heavy apps, would my Mac have trouble running them?

I never really ran OS via USB so Im not clear here.

I always thought USB would only affect transfer speed but would this affect the performance?
I do want to play some games on here but on VMware Fusion, too heavy.
If I run BC through USB and play heavy games or heavy apps, would this still cause the lag?

Thanks.

EDIT:
Wow, huge mistake here sorry.
I tried booting BC on my external HDD and it wouldnt even show up on the list...
Is it really impossible to boot any Windows from USB?

 

[dusk007]

Only in so far as it is like running an OS on a slow HDD.
USB adds some latency.
As it seems you would still use USB 2.0 that would also limit die Bandwidth to about 35MB/s which is half to a third of normal 2.5" HDD.
With USB 3.0 that difference would largely disappear.

It is just the HDD like loading stuff and writing stuff. Ultimately performance is the same once the data is in RAM.
In a game you get the same FPS only loading the level will take 2-3 times longer.

 

[gentlefury]

As far as I know, mac is the only OS you can boot off a USB drive. It won't let you boot windows.