Frequently-Asked-Questions.md

@@ -3,6 +3,17 @@
 # My SION files are HUGE! What can I do?
 See [SION File Defragmentation](Usage#sion-file-defragmentation). Note that you can still load the defragmented SION file into python, see [Linktest Python Reader](Linktest-Python-Reader), and it can still be used to generate reports, see [Linktest Report](Linktest-Report). After defragmentation the file can be further compressed using any non-lossy compression tools. The resultant compressed file can no longer be loaded into python and hence reports based on it cannot be generated unless the file is decompressed first.
 
+# Linktest Report (the python tool) takes too long. Can it go faster?
+Probably, here are a few things that will speed up report generation:
+
+1. Defragment the SION file before using it to generate a report, see [SION File Defragmentation](Usage#sion-file-defragmentation). This will speed up loading the data into python. However, if you only plan to generate one report this is likely not worth as the time gained in making the report is lost during the defragmentation of the SION file.
+
+2. Use a newer version of Python or MatPlotLib. Although the report tool was originally developed for Python 3.8.5 and MatPlotLib version 3.3.1 upgrading MatPlotLib version 3.3.4 improved a 2 minute run using a defragmented SION file by approximately 15%. Upgrading to Python 3.9.0 cut the time to just above 1 minute. The problem is mostly the slow MatPlotLib back end for generating plots. The backends are optimized for quality, not performance. Profiling indicates that for larger SION files, 50 MiB and above, the MatPlotLib back end takes up about 80% of the compute time of the report. 
+
+3. Use the supplied pingponganalysis tools. These create postscript files that can be converted to pdf. Generating a comparable PDF report to the above mentioned 2 minute report only takes about 5 to 10 seconds. Please note that the pingponganalysis tools are only kept up-to-date with the current version of Linktest.
+
+4. Read the SION files directly into Python and inspect the data there using the [Linktest Python Reader](Linktest-Python-Reader). This does not substitute a nice and easy to read report but gives you the flexibility of looking at the data more in depth or to produce figures that better fit your needs.
+
 # What do the weird unit prefixes, like ki, Mi and Gi, mean?
 TLDR: They are binary prefixes.