I presume the unit is new and not networked based on your post.
If you have a mapping card, I would change the unit to use the 'Lowrance' internal map to see if that works ok. If it does, then there is an issue between the unit keeping up with the mapping card. I know when I use a mapping card, the unit doesn't zoom in/out as fast but I haven't noticed any degradation in the cursor keeping up like you are experiencing. I would confirm Heading Up is the selected orientation - see #4 below.
I would first try a SOFT reset to see if this clears the issue. A soft reset will retain wpts/routes/trails. Anytime I do a soft or hard reset, I save my settings. For instance, I do not like to hear the beeps. After resetting the unit, I then load the saved settings. All my settings are then restored to what they were prior to the reset, hard or soft. Refer to the manual or Lowrance website for reset steps.
1. Confirm you have the latest software. Pages/Settings/About. Latest is Release Date: 16 May 2018; Version: 18.1 / 59.1.86
If not current, go to Lowrance Update
and follow instructions. This can also be accomplished using wifi on your unit.
2. Pages/Settings/Network/Data Sources/GPS Make sure the proper device is checked. If the 'All Data' is Global, I suggest changing to Local by touching the far right arrow and selecting Local.
3. Pages/Settings/Satellites - out on the water you should receive 10 or more satellite connections on a nice day. I get 10 active satellites just sitting in the upstairs office with the unit hooked to a portable battery.
4. Pages/Chart icon/Chart Options/Orientation - make it Heading Up. If you do not understand differences between Heading Up/North Up/or Course Up refer to documentation.
a. If you have a used unit without documentation, go to the Lowrance site to download to the computer. This PDF file and also be loaded to your unit so when on the water, easy access to the manual will be available to you. Extra tip: Pictures can be also be stored in the unit. As I recall, only .png and .jpeg files are valid. Use your imagination as to how this can be helpful.
5. Call Lowrance Customer Service. They get bashed on TFF a lot but I've have always had good experiences with them. If the queue is long, they will tell you your number in line, leave your phone number. They do call back. If you don't answer because you don't recognize the number, you'll have to start the call again.
Maybe someone else has some suggestions to try. Hope this helps.