We are announcing the End of Life (EOL) of the optional PDQ Agent beta from our existing products. See this blog post for more information https://www.pdq.com/blog/pdq-agent-status-update/
You experience Inventory agent related performance issues when scanning machines with the Inventory Agent installed, when deploying to machines with the Inventory Agent installed when using PDQ Deploy, or when several hundred machines have the agent installed generally. These issues often present themselves as, "Unavailable" for the Inventory Agent status.
PDQ.com is aware of these performance issues and is, and will continue, actively addressing them. In order to ensure agent-related scanning from PDQ Inventory and agent-related deployments using PDQ Deploy happen accurately, we force significant amounts of checks and balances between the Inventory Agent and PDQ Deploy and PDQ Inventory. This is temporary and will be optimized in later releases.
We recommend installing agents a few (less than 50) at a time to see where your individual threshold might be. Furthermore, it is recommended that when agent installation is greater than 150 total that you wait a minimum of 10 minutes before installing additional agents. This will allow the agent to timeout should there be a performance issue. In most cases the limiting factors are disk I/O where the database is stored, and whether the server is running on a Server or Desktop OS (Server will perform better).
Again, this is temporary in order to ensure the proper communication between the Inventory Agent, PDQ Inventory, and PDQ Deploy.