I vow to not use any cloud based software. Anything I have tried so far has been too sllow.
Speed would be the least of my worries - did you hear what happened to Tinkercad? Probably the easiest to use online 3D CAD program around, designed to allow you to quickly create models, etc - store them online or download the an STL file to send to your 3D printer (or upload to several 3D printing services if you wanted). I had heard about them some time ago, then about a week or so ago I decided to give them a longer "try" - and inside of a couple of hours, I had designed a simple bracket meant to hold a laser module (like something you'd mount on a robot or such). It was accurate down to a fraction of a millimeter; I was seriously tempted to have the STL file printed. I realized that this was the software I had been looking for to jump into 3D printing - CAD software is anything but easy, but they had made it easy - extremely easy, and affordable, too.
Then a couple of days later, they sent out a press release stating they were discontinuing the software to focus on a different market segment which would be based around the distributed 3D engine they had created for processing the Tinkercad modeling - and this new system would be for the simulation market. Tinkercad is no more.
...and there isn't a comparable piece of software to replace it, either. I started playing around with other options - the best I have found - so far - has been FreeCAD - but even it is no where near as simple and easy to use as Tinkercad. Shapesmith is a nice online and similar piece of software (and open source and free), but it still has a long ways to go before it can be like Tinkercad. Other offerings either won't work for me (Sketchup is Windows only - and barely works in Wine - and isn't simple to work with, either) - or are way, way too complex (Blender, for instance). I've thought about things like OpenSCAD (and OpenJSCAD, etc) - I like the nature of "program your parts" - but at the same time, it seems a bit abstract.
Tinkercad had built up a great community, got a lot of great testing, then tried to switch to a pay model that people apparently balked at (personally, I thought $20.00 a month was an absurd bargain for what you got); now that community has nothing to replace it, and likely won't support anybody wanting donations to fund a development effort, either (since they wouldn't pay for access for the low-cost Tinkercad offering)...
I can't blame Tinkercad for doing what they did - they need to make money to survive as a business, and apparently, there isn't money to be made from 3D printer enthusiasts for easy-to-use 3D CAD software (which I don't get - it's the software that's the toughest part of 3D printing - at least, if you want to do anything custom). Even so - they pulled the rug out from under a lot of people - and now those people have few options to select - currently - on where to go for similar software.
Cloud software support that can just go "poof!" one day reminds me of proprietary closed-source software, that can easily do the same thing (or the company go under) - I guess that's why I am now throwing my lot in with open solutions at least as far as CAD goes - as well as circuit design. Hopefully more people wise up and get tired of being "burned" by proprietary and closed source offerings.
Something makes me doubt it, though...