But if downloading apps becomes the norm again (like every online store asking you to get their app and an extra app for a discount program), I expect that socially engineering less technical users into downloading malware will become much easier.

How many current developers optimize their products for speed and energy usage?

I can see the very opposite happening: half-baked apps, whose massive portions were written using free-tier AI output, hogging gigabytes of RAM and four processor cores while the cursor is idly spinning and the laptop is becoming hot.

Compared to the past (and my memory goes back to Netscape Navigator 3, old person that I am), modern browsers seem to be technologically fine.