Image Acquisition Toolbox Jitter (GigE)

Up until now I was using FLIR's software to acquire data from an IR camera, but because of synchronisation limitations, I am now using the Image Acquisition Toolbox. However, the timestamps are problematic.

The camera itself allows to choose between 6, 12, 25 or 50Hz.

When looking at the timestamps obtained from getdata, the intervals between frames appear extremely variable (here for 25Hz):

I used the simplest code possible to troubleshoot this (and when using a simple RGB camera, the variability is minimal), here it is:

imaqreset
ThermalCam = videoinput('gige');
ThermalSource = ThermalCam.Source;

% Device-specific
ThermalSource.IRFormat = 'TemperatureLinear10mK';
ThermalSource.IRFrameRate = 'Rate25Hz';

% Acquisition
ThermalCam.FramesPerTrigger = 250;
start(ThermalCam)

wait(ThermalCam,12)

[ThermalData, TimeStamps] = getdata(ThermalCam);

Choosing the lowest framerate does not improve the variability, and I tried to adjust the packetsize and packetdelay values (both after manual and automatic adjustment of the packetsize), just in case, but it doesn't seem to influence the jitter (I tried the CalculatePacketDelay function provided in a different post).

The connections themselves are exactly the same as when I record with the FLIR software, which yields a pretty constant framerate but can drop a few frames.

Are there additional parameters to adjust to obtain a more constant framerate, or a different solution?

Thank you