The world could run on older hardware if software optimization was a priority

If dynamic array bounds checking cost 5% (narrator: it is far less than that), and we turned it on everywhere, we could have computers that are just a mere 950X faster.

If you went back in time to 1980 and offered the following choice:

I'll give you a computer that runs 950X faster and doesn't have a huge class of memory safety vulnerabilities, and you can debug your programs orders of magnitude more easily, or you can have a computer that runs 1000X faster and software will be just as buggy, or worse, and debugging will be even more of a nightmare.

People would have their minds blown at 950X. You wouldn't even have to offer 1000X. But guess what we chose...

Personally I think the 1000Xers kinda ruined things for the rest of us.

It doesn’t work like that. If an image processing algorithm takes 2 instructions per pixel, adding a check to every access could 3-4x the cost.

This is why if you dictate bounds checking then the language becomes uncompetitive for certain tasks.

The vast majority of cases it doesn’t matter at all - much less than 5%. I think safe/unsafe or general/performance scopes are a good way to handle this.