New To CNC and Mach3 ...
I have successfully created my code and its running ... G Code from Fusion 360...
The Issue have is the tool isn't moving smoothly on a simple curve ... The Feed rate drops considerably and the tool "judders" as it completes the cut ...
Feed rate isn't set high, just over 1300 but during the cut it drops to 4-500 and is juddering through the cut almost stop starting through the sweep.

Any help would be great ... Many Thanks

1300 what?  Whether inches or mm/minute sounds pretty fast to me!  What are you cutting, slot, surfacing, pocket?  More information please!

1300 what?  Whether inches or mm/minute sounds pretty fast to me!  What are you cutting, slot, surfacing, pocket?  More information please!

Thank you for your quick reply ... I've attached a Picture of what I'm seeing when running the code ... the Top Value is 1350 and the Units/min drop to below 600 units/min ... When this happens the tool almost starts and stops juddering along ... When cutting in a straight line there is no issues.
Ive attached the G Code as well ... Cutting a Small Part out of Aluminium
Sorry I'm new and getting my head round it.
Thank you in advance.

Please confirm, is your machine set up for mm or inches?  Either way 1350 strikes me as a rather large feed rate.  There aren't a lot of "F*********x" commands in your program.  One near the top is
G1 Z-6.865 F333.
so that will set a persistent feed rate of 333 somethings until there's another one.
Then further down you have...
(BORE2)
G0 X69.365 Y65.497
Z6.
Z2.
G1 Z0.635 F1350.
where you set a 1350 feed rate.  Then I see lower down another 333

Seems like a very ambitious program for a first try.  Try reducing the feed rate to something much lower perhaps?  200mm/min? What machine do you have?  I had a quick try at simulating the gcode using Camotics and it made no sense, just started a small hole, buried the tool, then went haywire.

At 18000 RPM its only .07mm (.003") per rev so I would put a G64 in at the top of the code and see if that helps.