Elements are not distinguishable, like power-ups from bullets, etc
Make them simple color based power ups. Words, letters or even icons may be too hard to distinguish at fast speeds. Make powerups one color and nothing else that color.
I start to feel dizzy and uncomfortable
Maybe you're getting too old to play those types of games :) This is likely a symptom of the other issues, solving those will probably help with this. Lerping movements with the camera and zoom will help with this. Jarring quick motions or quick changes in perspective can induce these feelings.
There isn't enough time to see what's coming
The faster the player goes, the farther out the zoom should be. Many games zoom out when using a boost/afterburners. Since you're going faster you need more time to react. The farther out you can see, the more time you have to plan for what's coming. Additionally, having indicators at the leading edge of the screen may be useful. For example if some kind of obstacle is coming that the player will need to use a special ability to avoid/destroy. Show an indicator at the leading edge of the screen to let them know it's coming before it comes into sight.