Hi Juan and Vincent,
I have isolated the problem to DynamicPSF and have a simple script that will let you reproduce the problem on Win7.
Files are in Forum Shared Files mschuster/performance.
1) Launch PI.
2) Open the image integration.fit.
3) Run the script performance.js, choose the file barycenters.dat.
4) Make a note of DynamicPSF performance.
5) Repeat steps 3) and 4), note the performance on each run.
Here is an example of the performance results I saw for 5 successive runs of the script:
3.9s, 6.2s, 8.6s, 11.1s and 13.7s.
The file barycenters.dat is a binary formatted file containing the coordinates of a large set of star barycenters in the image. These barycenters were detected by StarAlignment and written to the file by different script.
The script reads the barycenters, initializes the DynamicPSF instance appropriately, and then runs the instance.
Note: there is a possibility that the script is not initializing the instance properly. If not, please let me know!