Nokibar have posted the above video in which they tested the performance of the Windows 10 Mobile Technical Preview running on the Nokia Lumia 925 with Windows Phone 8.1 on the Nokia Lumia 920.
The hardware of both devices are more or less identical, and it is clear from the video that Windows 10 Mobile is somewhat slower than the older OS. This is however easily explainable due to debug code being present in Windows 10 Mobile, vs WP8.1 of course being more optimised.
What I do however find worrying is the is slow launch of the Windows 10 native apps such as the calculator at the 2:21 mark. Much like Xbox Music app in WP8.1, I suspect this will be an enduring performance issue going forward.
Are our readers concerned about this problem?