[fitsbits] Fastest way to read a binary table

[Thierry Forveille]

William Pence writes:
 > In fact having too many buffers will hurt performance
 > because CFITSIO then spends more time searching to see if the needed FITS
 > block is already loaded in one of the buffers.  Recent tests on a 'typical'
 > program seemed to show a slight improvement in overall I/O speed by
 > increasing the number of buffers to a couple hundred, but increasing it to
 > several thousand caused the program to run slower.
 > 
Is that because CFITSIO performs an O(N) search through the buffer list? That
would certainly make sense for N=50, but for a few thousand it probably
becomes worth using hashing instead.