The eurogamer more extensive tests didn't say the Switch was immune from frame rate dips just their original assesement had them about equal but further play testing showed the wii u frame drops were a little more often and a little bit lower at times so the Switch wasn't quite as bad. Even the Switch in portable mode has frame rate drops except much rarer again.
The issue with wii u may be its weak cpu performance or memory bandwidth bottleneck but with Switch it's likely to be memory bandwidth bottleneck for the simple reason in docked mode the Switch comfortably outperforms wii u in cpu and gpu terms even allowing for increased resolution but its memory bandwidth spec is poor much less than ps3 and 360 for example.
To be honest I'm used to low frame rates in wii u games. Many third party games struggled on the hardware. Black ops 2 which was 60fps on 360 and above 50fps on ps3 was often in the low 20fps on wii u.
We are already seeing many Switch games with frame rate issues if anything more so than was common with wii u at the beginning.
What really makes this an issue is after you've stopped admiring the beautiful graphics and design you realise Zelda isn't a great technical achievement compared to other formats. It's graphics are not cutting edge by a long way they are quite basic with limited texturing and model detail. Nothing the ps3 or 360 couldn't do. Maybe lack of memory would force them to have extra loading sections but the actual graphics are not technically impressive.
