Is it the loading of packages that is slow, or the responsiveness of Toad after lots of packages are loaded? How many packages are in your schema?
Do you think the problem could be in the database? There should be status messages that give you an idea when the query executes, and when it is fetching. If the execution time is slow, the problem is in the database (out of date statistics?). If the fetching is slow, it could be the database, the network, or Toad.
I’ve got a local database with 50,000 packages all in one schema. For me, Toad 12.1 loads those packages into the schema browser in less than 10 about 5 seconds.