You got a lot of 32bit plugins installed. To use them in the 64bit version of Renoise, Renoise must bridge them. This can delay the load time significantly.
The plugin servers are still active in the 32bit version, so it seems you have the “Run all plugins in sandboxes (➜separate process)” option enabled.
So, if you rely on your old 32bit plugins and most of your plugins are 32bit, use the 32bit version of Renoise. Then no plugin “bridging” is necessary. Then turn off the “Run all plugins in sandboxes” option.
Alternatively, install 64bit versions of your most important plugins and use them instead if the 32bit versions in a 64bit Renoise.