It's time that i release my main model, i've not much to say about it, it's a 1.5 merge of a merge of a merge of many merges, and it's only 2gb! :P
i usually set 70 sampling steps and 70 high resolution steps with the upscaling set to "latent"
without the upscaling at least 40 sampling steps from what i've seen.
To keep a reasonable resolution and speed at the same time try 360x640 upscaled (a 2x is enough) so it's a 720p pic