I noticed that there are two types of priorities in : memsave prio and std priority. When does it switch between the two? Is there a threshold parameter that can be set to influence this switching?
Yes, parameter memory/savefac:
# fraction of maximal memory usage resulting in switch to memory saving mode
# [type: real, advanced: FALSE, range: [0,1], default: 0.8]
memory/savefac = 0.8
See also https://scip.zib.de/doc/html/PARAMETERS.php for documentation of SCIP parameters.