Start without internet and that can save you minutes startup time. It's not a problem when one or two mods do it, it's barely noticeable, but in larger modpacks with hundreds of mods it adds up and you have to wait for hundreds of connections, sometimes to servers that are down or very slow or even worse, start throttling you because you're doing too many requests too fast and those connections take forever to time out. Because lots of mods check for updates and download lists of patreons and news and whatever other stuff they feel like they just must do. This is true for pretty much all large modpacks. I had a power outage in my area, power came back but my internet didn't come back for a few more hours. Just rediscovered something that I used to know and forgot.
