- When a request in a queue, waiting for a network connection it is considered blocked Blocking happens when there are too many simultaneous connections made to a single server over HTTP.
- DNS resolution is the time it took to do the DNS lookup. The greater number of hostnames, the more DNS lookups need to be done.
- Connecting is the time it takes for a TCP handshake to complete. Like DNS, the greater the number of server connections needed, the more time is spent creating server connection.
- TLS handshake is how long it took to set up a secure connection.
- Sending is the time taken to send the HTTP request to the server
- Waiting is disk latency, the time it took for the server to complete its response. Disk latency used to be the main area of performance concern. However, server performance has improved as computer memory, CPU, has improved. Depending on the complexity of what is needed from the server, this can still be an issue.
- Receiving is the time it takes to download the assets