You can get Speedtimize from the following marketplace:
Gumroad - https://gattalupagames.gumroad.com/l/speedtimize
Blender Market - https://blendermarket.com/products/speedtimize
Speedtimize can be installed like any other Blender addon. Download the .zip file containing the addon from the marketplace.
In Blender go to Edit > Preferences
Go to the Add-ons tab and click the Install... button
Navigate to the folder that contains the Speedtimize zip file, select it and click Install Add-on.
With that, the addon has been installed. However, it is not activated yet.
To activate it, place a checkmark next to the Speedtimize addon.
You can also see all the info about the plugin here, such as the version, docs, etc.
You are now ready to use Speedtimize. A new tab called "GTLP" will appear in the Side Bar of the 3D View. All features of the addon are found there.
