big O lang. IMO time and space complexity are super relevant when you are doing bare metal programming(assembly/C stuff). Yung tipong super constrained yung memory at yung processing power ng hardware.

Pero if you are doing backend stuff. With auto-provisioning, unoptimized but well tested and well architectured codebase(kahit sabihin mong may self-contained spaghetti sila within) is better than super optimized code na di mo na mabasa kasi taena sobrang talino ng gumawa. At least kung self contained yung spaghetti with tests to boot, madali lang i-refactored

If you are doing development for business, code should be a common commodity.