My game runs fine. I don't have a powerful computer and I have a bunch more script mods on top of those you listed.
I assume you already deleted your localthumbcache file (should be done before every session). Whenever my load time starts getting long (in my case, always after an update, the game or the mods), what I do is delete the NWP folder in my saves folder. Last time I wasn't sure which one was messing up so I also ran the WW.fix command and was getting ready to do all the steps for cleaning out my save game as listed here:
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. Fortunately, deleting the NWP folder and running the command was enough.
A few pages back, someone mentioned the MEGA folder has the beta version of NWP and not the stable release so make sure you're running NWP 2.1.7n and not the beta 2.2.0n. I got mine from yiff. If all else fails, you might need to delete the cfg files from MCCC but I'd try everything else first because that will reset all your settings. Also importantly, as someone else was just discussing, your antivirus might be interfering. I have Norton and even though I whitelisted the game, it will still stop the script mods from accessing game files and I start being plagued by LEs. I have to go in and disable its data protection feature every time I play the game.
God modder CmarNYC has an auto HQ converter program and I just checked, it will in fact allow you to select the package you want and convert it from HQ to standard. It's at MTS:
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Also, make sure to go to Studio->content management -> batch fix -> CAS -> disallow for random. That way random townies won't be spawning with resource heavy CC.