Double-spaces between sentences are an artefact of outdated publishing technologies (typewriters). Today, they are an unnecessary visual distraction that takes away from your message.
No one returns printed novels because there’s only 1 space between sentences; no one complains that websites look too much like professional publications.
You could similarly argue that typing with a telegraph key is faster than thumb-typing on a phone — and you might even be right — but it just doesn’t matter: it’s obsolete.
There are those who advocate honouring the writer’s intentions in this regard; but writing is for the reader, not the writer.
People can be understandably hard to convince on this point; old habits die hard. For a second opinion — from an expert typographer — read Paul Butterick’s One space between sentences.