Here are some factors that seem to affect the speed of the Picture XCMD:
* The amount of RAM allocated to HyperCard.
* The size of the picture file.
*╩The type of compression used.
* The parameters you pass to the Picture XCMD.
The method used to compress an image affects its final size and the speed
of decompression. Faster display speed may be achieved by allocating more
memory to HyperCard. However, the method of compression is a more important
factor.
The Picture XCMD seems to be able to display files quicker if you do not
pass a parameter for bit-depth (fifth param). Do so only if memory
conservation is important. Instead, let the XCMD figure it out the
appropriate bit-depth. If you try to display a file at a lower bit depth,
it takes time to convert.
If you pass 0 for the bit-depth parameter, then the XCMD does not set up an
offscreen buffer. Hence, the window will seem to appear immediately, but
the picture may take some time to get drawn into the window (it is drawn as
it is decompressed). This method will give you slower updates.
This article is adapted from the Claris Tech Info database.