There is also an option for complex layers "Image Render" in Object Options (or Render as Image with right click).
This will keep the image of the layers that are not changing

I've been thinking about VS performance,

@VectorStyler Does locking a layer and/or turning off the eyeball improve performance?

You should be able to switch off anti-aliasing and degrade view quality of just selected objects. This is a golden mean between total degradation of all elements and total quality of all objects. This has always been possible in Xara, where you can select the object with FX and blends, and toggle on anti-aliasing. The left is without anti-aliasing, the right is with. On the same canvas.

I am designing a typeface, and kept run into the problem of wanting to find hyper-accurate measurements. And I thought, you know what I'd like? A caliper on my screen! And here it is: https://www.iconico.com/caliper - It would be a great addition to have a calliper tool with built in angle measures in VS.

Not for screen pixels, but all widths/heights path lengths or angles can be measured using Measurement variables created from the Variable Values panel

A question: how do those other programs handle if these lines, grids, are rotated? how does snapping of a curved shape works at corners of those rotated grids?

Guide Layer

Exists in VectorStyler also.

I start with a 6X3 Table. And then merge cells very quickly and get this:

Next I move the Table into the guide layer.

Voila. Now it's a grid/guide:

This is exceptionally useful.

Ruler highlighting. This helps ensure that when you're moving objects, you can actually see the position without guessing. Available in many, including my beloved FH.

Layout view. This was once upon a time available in FreeHand. But now Scribus has revived it. It can either be a dedicated view like outline view or if you zoomout, you see the text density and weights. Brilliant stuff.

Pattern-mode: This is actually one of my favourite PL features. It allows you to turn your entire canvas into an instant repeating pattern. This means that you can quickly design a single tile and turn it into a pattern with a single click. You can also quickly hide the panels and see how the pattern looks:

Like so!

It's brilliant. And it is editable live. It is also incredibly fast.

Edge Gradient: http://www.vectorqueue.com/imaxes/scurve.MP4...

a.k.a Diffusion Curves

not exatly the same as the one you refer to, but very powerful too, especially with all the new repeater geometries added

video : https://somup.com/cTXtjLRI6R

"This would require the use of a modifier key. And I need to know what is the parameter to be changed (stroke width?)" - Why would you need a modifier key? Checkout either Affinity or PS. All scrubbing actions are done without modifiers. On both mouse and stylus. What do you anticipate as a problem?

Example please: Here's menu scrolling in PL: https://imgbox.com/19gtnaMV - It works across every field menu. It also works when I point at a numeric field and scroll. The number goes up and down, and the slider related to that numeric field slides up and down. VS already allows this for stroke, opacity, etc. I can scroll on the slider too and get the same response. This is highly immersive.

A bit difficult, but can be done. - Completely understand. This is a genuine workflow booster. Let me show you an example. Here's the example for Xara, where literally everything under the sun is found in what they call Gallery. Fills, Strokes, Bitmaps, Fonts, Names, Colours, and Assets. You can drag anything and out of the gallery from the page to the gallery and vice versa: https://imgbox.com/uWy4ETGm

Did you see the copy tool? There is a dedicated copy tool.

ok yes I had seen that but I was thinking more about the literal "copy" paste basic function tool at the bottom - i see what you mean now. there is certainly some interesting and fun abilities that can be implemented quickly with the copy tool you highlighted. I could see it as an extension of the repeater tool

Now you have the mirror tool correct?

But that's not really the only possible transformation possible is it? Most design software cover just 4 major transformations.

1. Rotation
2. Mirroring
3. Shearing/Skewing/Warping
4. Scaling

But there are 2 more important transformations, which are not covered.

1. Translation
2. Glide reflection

A complete transformation tool would do all of it. And this copy tool is actually a good prototype of how it could work.

In fact, every single of the 17 possible wallpaper group - that's every repeating pattern conceivable on a 2D plane - can be generated by just with 4 transformations. Translation, Mirroring, Rotation, Glide Mirroring.

I will try to implement these, but some assistance needed:

1. Scrubbing: This is sin qua non if you want to make VS stylus-friendly. Merely pushing the pen down and dragging should allow the user to change parameters. Sliders are only useful when the user needs fine control. In most cases, such fine controls can come during the tweaking stage. When the user is designing, scrubbing allows total immersion into the work.

This would require the use of a modifier key. And I need to know what is the parameter to be changed (stroke width?)

2. Scrolling: Scrolling through fields should take the user up and down any list. Again, this makes for a very immersive user experience. Clicking and selecting disrupts flow.

Example plesae

3. Increasing parameters factors of 5, 10 and 50. Ctrl Scroll through parameters should increase it by multiples of 5. Ctrl + Shift + Scroll by multiples of 10. Alt Scrolling by multiples of 50 - where this is possible.

Is this in number fields?

4. To and fro panel interaction: Imagine you have the symbols panel open for instance. Instead of going through clicks, you drag and drop the object into the panel. Boom! Done! So all styles and presets panels could work this way, making for a highly interactive workflow.

A bit difficult, but can be done.

Look at their very clever copy function.

I went to check it out but did not see anything out of the ordinary with the copy function. No doubt I am the weak link here in understanding what was clever; would you be willing to elaborate on it when you can?