For the image I'm working now, I was using the Faded Industry warehouse model from Daz and the preset shaders in ACSEL. Studio became unresponsive for quite some time, but I let it finish as I hadn't saved my mat settings yet and really really didn't want to lose them (several hundred as usual).

I went and made brownies, then came back after 40 minutes to check the progress. Studio finished/caught up, then I went back to the materials tab to see what was going on, if an MLIE image snuck in (there are none) which has been the only thing that slows Reality noticeably for me. 

I closed Reality, saved my scene, then reopened all and checked the materials tab. Not sure if the ACSEL settings took hold, but the maps were all over the place in the modifier tab, as well as the slider themselves. I'll grab a screenie for you in a sec. 

Edit: Brownie making fully optional ;-) 

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