Harald Fauland

In my humble opinion: If your website hits an amount of visitors where performance gets critical, you can afford to hire technicians to do your job! ;) It doesn't matter what stack you choose, i would go for the one where i am most skilled at and since you want to do some ML Python and Django along with it are the obvious choice.

Since you love Django, no need to change that. Flask has no batteries included and once you are used to the ORM that Django provides there is no going back. For the frontend part i would go with Svelte, since it's such a blast to learn and code. Google the same code for React and Svelte and you will know why you should choose Svelte.

Since you want to stay on one stack, python os your best choice. The language doesn't change so much as JS and no one knows where node/deno is heading.