GL-MT6000 High Memory Usage with External Storage?

Currently running 4.5.2 and when I connect external storage either a USB stick or external HDD formatted in NTFS and start a webDAV share, my memory usage seems to spike up quite a bit. I run AGH with a few big lists and before connecting the external media, it sits anywhere from 45-50% memory usage and after connecting the external media and accessing files, it’s currently sitting at 85% memory usage.

Edit: With external drive connected, it reads as 85% Used, 45% Cache. When I stop the webDAV share and eject the drive, it goes back down to 53% Used, 19% Cache.

Edit 2: This also happens when creating and using an SMB share, the memory usage went up to 96% and when I ejected, back down to 51%.

After using external storage for reading and writing, some data will be cached temporarily. It is normal for the memory usage to increase. After reading and writing are completed, the used value displayed by the free command will not decrease. The remaining memory is subject to the available value.