Why is StratixIVGX device's compilation time so long?

I'm sure there are a ton of different factors that contribute to the build time, but we found that the biggest impact on improving build time was getting a build box with the latest corei7 with the fasted supported RAM and overclocking it. That brought our SIV GX builds down from around 2.5 hours to just over an hour.

EDIT: Should have mentioned that we run linux on the build box and executing the builds from the command line also improves the build time.

We also noticed that the Scaler I has an extraordinarily long build time relative to Scaler II.