An issue with the PLAN command

This is just more of a general wondering; there seems to be some difference between the functions of the PLAN command and pressing the top part of the ViewCube. In my head these should do the same, but the latter is much heavier on my system, and may leave it unresponsive for many seconds, while the PLAN command is pretty much instantaneous. Why is this?

Because of the above issue, I usually use the PLAN command. The drawback of this is that once I use it, the whole model is made to fit onto the screen in addition to aligning it to your current UCS. This forces me to zoom back in to whatever I was currently working on - and if the model is big and complex, this gets annoying. So the question becomes - is there a way to align the drawing to the chosen UCS without it also zooming out to fit the entire model at the same time?

First question: This is just off the top of my head but when using the cube, you are still in 3D mode. More calculations, more time. Plan switches it to 2D mode.

Second question: Don't know.

If you use zoom;p right after plan command you be back to area you were working before.

Create macro for yourself: plan;;z;p;

... I usually use the PLAN command. The drawback of this is that once I use it, the whole model is made to fit onto the screen in addition to aligning it to your current UCS. This forces me to zoom back in to whatever I was currently working on - and if the model is big and complex, this gets annoying. So the question becomes - is there a way to align the drawing to the chosen UCS without it also zooming out to fit the entire model at the same time?

As a recovering PLAN Command user myself, for some time now, I've instead been using DVIEW to 'twist' my view & crosshairs... I've also coded myself an 'untwist' command, which effectively restores WCS, plan view, etc. without zooming to extents.

Cheers

Use the VIEW command and automate the process so you can save a view with a few keys or pick of a button, and then be able to recall it with another few keys or another button.