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Incorrect or missing information? High speed Downloading

If you are blessed with a fast connection (50MB/s and over) and are not getting the full speeds you require, you can try the following:

  1. Make sure sabyenc is installed by checking the first page of the Config. If you used the installers on Windows, macOS or a repository/pre-built package, this will be present. This will speed up decoding as it will use C code instead of python code. More information here.
  2. Set the Article Cache Limit in Config->General. This will keep articles in memory and not write them to disk (which is slower). Depending on how much RAM you can spare, two good values are 500M (the M denotes megabytes and is required) or 1G (1GB). If you download a lot of rar files that are 200MB or larger then use the latter value. The cache will only be used when nessecary, cache usages above 400MB are rare.
  3. Check if logging is set to only Errors/Warning in the Status window. Especially the +Debug setting writes very frequently tiny bits of data to the disk. This increases CPU load for the writing and occupies the disk.
  4. For larger queues it can be beneficial to enable Only get articles for top of the queue in Config->Switches, as iterating through the queue to get the next article takes substantial amount of CPU power for large queues.
  5. Investigate your connection count in Config->Servers. It may seem counter-intuitive, since more connections should be faster than fewer connections, but if you use the 50+ connections some hosts give you the overhead from constantly opening and closing connections can slow you down. So start at the max allowed connections and slowly lower your count until you max out your speed. Or do it the other way round: start with 5 connections, measure the speed, and raise to 7, measure again, 9, measure again, etc. Normally 10 connections are enough.
  6. If you use SSL to connect to your newsserver, try changing the SSL Ciphers. This will sightly lower encryption strength but can greatly increase download speeds.

If none of the above methods make a difference, have a look at how much CPU is being used while downloading, if it is at 100% it is likely your processor is too slow to maintain high enough speeds. In the Status window ( ) you can run a PyStone CPU performance test. ARM based systems (NASes for example) will show much lower number (below 25000), and will have a lower maximum download speed than PCs with a current Intel/AMD CPU with a CPU Pystone available performance of 40000 or higher.

Another limit could be your disk write speed, in the Status window ( ) you can do a write test by clicking the icon. This is the speed at which SABnzbd can write to your folders, if it is lower than expected you should check your hardware and software settings.