In MARS activity you can see only the requests that are currently "active" on the Web API level. A "queued" request is not visible in MARS activity

1. It can give you a good insight of your current request status and of your request details (like number of fields, number of tapes accessed etc)
2. It can give you a very good indication of why your request is slow
3. It can provide you a lot of information that you need to improve the efficiency of your request like
   
   • how many tapes your request is accessing (in the MARS log output)
   • the reason why a requests is queued.
   • other users requests.

See Guidelines to write efficient MARS requests.

Many requests submitted by other users may be running in parallel consuming the services resources (MARS slots, Web-API slots, Tapes access slots etc). These requests may be very useful  to understand the efficiency factors.

• Compare the activity of your requests to the other users activity using the MARS activity page.
• See the reason that some requests are "queued" and how long they have been "queued".
• Have a look on the MARS logs about limitations like:
  • "In marsod-core, the total number of Requests from ECMWF Web API with 1 tape mount [source] is limited to 6"
  • etc