Try
import Pkg
Pkg.activate(temp=true)
Pkg.UPDATED_REGISTRY_THIS_SESSION[] = true
Pkg.add("Package1")
Pkg.add("Package2")
# Here is where it should really start
using Package1
using Package2
I actually had that for a while in my startup file.
Take a look at: GitHub - feanor12/Draft.jl: A small package to automatically create temporary environments in offline mode.
And a discussion about something similar is here: Speculations about the default environment (or a new draft environment)
Although I must say that for me those issues got less important now, but probably because I’m not currently dependent on a package with very large ttfx. Plots for me takes 15 s, and a second now with 1.9. My hardware is not much different from yours.