It's not inserting a single hole for every hole. Both methods uses a pattern feature.
The first method, you create a sketch, in a sketch and add a point, then you create a pattern out of the single point, and ask the software to add holes to the given sketch pattern.
The second method (which RonPaii explained is faster), you create a hole and pattern the hole. Both methods uses pattern. The difference is the pattern is used in a sketch, or the pattern is used on a feature.
But in either case, there are ways to prevent a fall in the performance when you have a lot of holes.
A very effective way is to lock the feature and ask the software not to render or rebuilt the feature. It means that once the grid is added, the software doesn't care about it and will not use its resources to validate it.
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In the above tree, I've locked the features I don't want to be rebuilt again, by dragging down the yellow line. The software will bypass them and pretend there are not there at all. I have all several thousands of holes in my 3D, but the software doesn't care about it.
As I said, I don't know about previous versions, but recent versions of CAD software proves that both methods are the same less or more. It's been proved that "Fill pattern" performs much faster than both above methods. In Fill Pattern, you don't even add a hole to pattern it. Solidworks creates one feature which contains both the seed and the pattern.
Here I have 2530 holes, and still the decrease in performance is very low. And if I lock the Fill Pattern feature to prevent future rebuilds, still the performance get better.
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I've never used Fusion, but according to all I read on CAD forums, everyone says Fusion is faster than Solidworks. It's not because of it being cloud base, but the way it manage things. Also most people I know, believe that in exchange to the speed, Fusion is much harder to work with (comparing to Solidworks) and has more short comings, specially when it comes to working with surface tools.
We've been forced to use cloud based Solidworks for a while, And I wish we could cancel it and go back to desktop.
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