curl/docs/libcurl/getinfo-times

An overview of the six time values available from curl_easy_getinfo()

curk_easy_perform()
    |
    |--NT
    |--|--CT
    |--|--|--PT
    |--|--|--|--ST
          |--|--|--TT
    |--|--|--|--|--RT

NT = CURLINFO_NAMELOOKUP_TIME. The time it took from the start until the name
     resolving was completed.
CT = CURLINFO_CONNECT_TIME. The time it took from the start until the connect
     to the remote host (or proxy) was completed.
PT = CURLINFO_PRETRANSFER_TIME. The time it took from the start until the file
     transfer is just about to begin. This includes all pre-transfer commands
     and negotiations that are specific to the particular protocol(s)
     involved.
ST = CURLINFO_STARTTRANSFER_TIME. The time it took from the start until the
     first byte is just about to be transferred.
TT = CURLINFO_TOTAL_TIME. Time of the previous transfer. This time does not
     include the connect time (CT), so if you want the complete operation
     time, you should add that.
RT = CURLINFO_REDIRECT_TIME. The time it took for all redirection steps
     include name lookup, connect, pretransfer and transfer before final
     transaction was started. So, this is zero if no redirection took place.