The DAW set up is really crucial when using 'VI's' and if you are using standalone and they are fine, then I'd really look at how the DAW is set up.
As far as RTAS is concerned, Pro tools has never liked VI's and the CPU usage has always been high with all of them, including arturia, NI to name 2.
Pro tools 10 has been a lot better with VI's, although you have to juggle your voices around a bit.
Another point is, software crashes! That's a given and you will always have issues if you can't find workarounds to certain known issues, this isn't just for arturia but every piece of software you own. But as the first post says, just use it to create and work around the gremlins and find a way to get things working for you. what works for one won't always work for you. Another huge issue is the workstation people are using to record on, if you can afford it, buy a 'music only' machine and don't use it for email or word or anything else that could break it. I have been on machines that have had all kinds of rubbis installed and it is always the case that something is conflicting on the machine.
Every few months, back up, nuke your drives and reinstall.
When I'm not that busy, I set aside a half day and back everything up, download all my latest installers and plug ins and install my system from the ground up, it really does keep stuff clean.
I'm not saying I don't have issues, I do, but by keeping your machine clear from freeware and all other manner of rubbish, keeping your system in tip top condition and working around certain issue you can really start to use the software as it was intended.. To create music
I find lots of people are content with finding issue with every piece of gear they own, but just because it doesn't work flawlessly all the time. Concentrate on creating and all these issue will slowly fall away.
Stuart