The reason this one hurts is the high constrast and high detail. With colours so saturated and so much detail it's more difficult to look at for long periods. The other ones you've done in general don't have the same issue or atleast not to the same degree.
The closest example in comparison to detail and saturation is
and in that one the black is instead a grey, so it's been softened and reduces contrast, alowing for less eyestrain.
Next closest is
, and in it you've done the same thing you've put the relativly low contrast purple as the majority, which makes the pink easier to handle. Also most of the shapes are represented as large and relativly unbroken so you don't have to focus very much on them to read them which means you've less time to be blinded by colours.
By contrast your current project has large quantities of pink, orange and yellow on black. Which is causing alot of the issue. I'm happy for you to continue to use the same pallet as you've obviously had alot of experiance with it. But it is something that would be very dificult to work with mainly due to it's blinding nature. It will be a case of how you use the colours in order to soften those tendencies. It's the same issue the older default ms paint pallets cause (when i was first starting and was a little kid stuffing around, i used to use the windows 95 default pallet and often drew on black. Then being so proud made it the background of the computer only to have my sister later lecture me on the apropriatness of my image as a background due to the pallet since high contrast backgrounds cause eyestrain, specifically her eyestrain xD), and it can be difficult to realise it's an issue because your so used to working with it. :]
But like i said don't let that stop you if your are set on this pallet. It's just the first thing that popped to mind when i was trying to look at the pixeling.