i notice a change if i add the min and max ram in the line like this for example:
# Xmx and Xms set the maximum and minimum RAM usage, respectively.
# They can take any number, followed by an M or a G.
# M means Megabyte, G means Gigabyte.
# For example, to set the maximum to 3GB: -Xmx3G
# To set the minimum to 2.5GB: -Xms2500M
# A good default for a modded server is 4GB.
# Uncomment the next line to set it.
-Xmx10240M -Xms8192M
i need to make more experiments but for now this apparently works.