There is a lot going on during any run of Voxel Link (VL). But for the first run in particular, all elements (levels, framing, tags) have to be written to the Revit model. It isn't really noticeable when you're modeling by hand but when you take 15 hours worth of hand modeling and compress it into 2-3 mins, it seems like an issue. Factor in whether the Revit model is on your local drive, network drive or in the cloud and the range of processing time for exactly the same model can be significantly different.

As a point of reference, we checked a rather large model. It was four stories with a total of 650 members (476 beams, 70 columns, 24 vertical braces), about 100k square feet. Each run started with a totally clean file - no families prepopulated so each new structural family had to be found and loaded and we had all of the plans annotated/tagged with reactions on both ends and section sizes/cambers/studs. That's a bunch of work.

The first test run had both the RAM and Revit models on the local C:/ drive of a desktop. The time to process everything from clicking OK on the settings dialog until the Summary of data transfer dialog popped up took 3.25 mins.

The second run had the RAM model on the local C:/ drive but the Revit model was in the cloud on ACC/BIM360. That processing time took a 'whopping' 15.5 mins.

The number crunching was exactly the same - the data was all intact, nothing was missed, all the plans looked the same - but writing all that data via the local desktop -> internal network -> internet -> cloud file just has bottlenecks written all over it. 

Updating takes a fraction of these times because it's a lot quicker to change a parameter (like section size) than add the element new.

So, why mention this at all? Mostly for awareness and planning. If you know the model will be hosted in the cloud, you'll want to plan for the extra time to import and update. Is there something wrong with VL? Nope. The calculation is the same either way. It just a function of getting that information from point A to B. Regardless, 15 mins is still way better than 3 days!