Here is working good too, for testing: 800 nodes in 3 minutes after a year not turning DHT on. Might be the number of peers, or even their DHT config, your torrents have?
You might wanna increase the simultaneous searches in the settings (which is directly related to "Running Searches" in DHT stats), that MIGHT increase the number of queries and search peers query.
Nodes aren't the only important aspect, there are the peer database that really matters, which is why DHT exists.
I got 100 peers in 10 minutes.