Graham writes an interesting post where he compares the impact of slow login and slow applications. It’s a good analysis and leads Graham to conclude that forced to choose he would go for slow login, because it’s predictable and infrequent and so can be proactively managed (ie do something else why you wait.
I’ve been mulling over the same issue – but without the nice graphics -when it comes to desktop and application virtualization, and I’m very keen to dig a bit deeper into the user experience impact of a collection of new technologies:
- Virtualised applications add a small performance overhead
- Streaming virtualised applications adds a significant overhead to launch time, especially in a VDI environment where caching is of limited value (although pre-caching in the image would be better)
- Virtualization of the applications configuration and the users personalised settings adds a further overhead to launch times
- WAN access to data adds a further overhead to application launch times
- We’ve yet to quantify for many niche applications whether non-persistent VDI images (where only the roaming profile is persisted at logoff) are going to be slower, maybe because they cache for performance in the local profile and assume that the users local profile is going to be there tomorrow 99% of the time
- Sharing server resources across many users, is likely to work out great on average, but I’m not 100% sure that it will be faster for peak CPU periods which often occur at application start-up
- Most VDI deployments encourage users to logoff frequently and that’s likely to increase as the logon/logoff cycle is required in order to update the master image, not only does this affect a few of the points above, but it also makes detailed user state preservation very important – ie saving which applications, files, scroll locations, browser tabs, window positions etc the user has open and restoring them when the user logs back in.
- I dread to think how regular logoffs would impact my productivity, right now I logoff once ever couple of weeks, and it takes me at least 20 minutes to close everything down and open everything up again, if I had to do this every day – the least of my worries would be the time it takes for the OS to boot.
So one things for sure, in the new word of desktop, end user experience performance monitoring is going to be pretty important.
