Hello folks, I will try the option to have the console stay open and see what is going on. The pack is quite large but when i was running it on Windows (Same Laptop) it would be a case of click play, minecraft opens instantly and starts loading the pack, so im guessing it is something to do with the Linux / Java setup i have now.
I will get back to you shortly with some news on what it is doing.
Sorry I also realise I didn't answer your questions very well. So yes the delay is between pressing Play in the Launcher and the Minecraft window actually opening. Allocated RAM was 3GB out of an 8GB machine with nothing else running.
Having watched the window it seems to hang for quite some time due to "Inpurecore" downloading a library file and then a few lines later loading an INpurecore file so I'm wondering if it's possible that I need to update / downgrade this mod (It's my own pack) and that this is just a coincidence that this has started happening since the move to Linux.
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Not so sure on that anymore, it's just slow!! I can see it loading all the mods like it does on the server side before it opens the window but it starts at 10:22. Now 10:41 and its still loading! Not normally this slow but the machine is currently under a bit more demand at the moment as im building a Windows 7 VM