CUDADot[] takes ~3x time compared to Dot[]

Question

It all started when specifying TargetDevice -> "GPU" in Classify[] yielded no speedup nor any activity in the GPU. Then I tried something simpler like CUDADot[], just to see that it is ~3x time slower than plain Dot[]:

<< CUDALink`
M = RandomReal[{-1, 1}, {5000, 5000}];

AbsoluteTiming[Dot[M, M];]
(* {2.72066, Null} *)

AbsoluteTiming[CUDADot[M, M];]
(* {8.20455, Null} *)

EDIT: Even after using CUDAMemoryLoad[], it still is slower:

<< CUDALink`
M = RandomReal[{-1, 1}, {5000, 5000}];

AbsoluteTiming[Dot[M, M];]
(* {2.29508, Null} *)

CM = CUDAMemoryLoad[M];
AbsoluteTiming[CUDADot[CM, CM];]
(* {7.47153, Null} *)
CUDAMemoryUnload[CM];

After all, perhaps the h/w is to blame, as the same slowdown in Matlab is also seen:

>> x = gpuArray([1:0.3:10000]);
>> tic; dot(x,x); toc
Elapsed time is 0.316340 seconds.
>> 
>> x = [1:0.3:10000];
>> tic; dot(x,x); toc
Elapsed time is 0.014257 seconds.
>> 

But the workaround (forcing the usage of low-precision floating point arithmetic, i.e. 32 rather than 64 bits) doesn't seem to make things right:

<< CUDALink`
M = RandomReal[{-1, 1}, {5000, 5000}];

AbsoluteTiming[Dot[M, M];]
(* {2.77907, Null} *)

CM = CUDAMemoryLoad[M, "Float"];
AbsoluteTiming[CUDADot[CM, CM];]
(* {8.0693, Null} *)
CUDAMemoryUnload[CM];

My environment, I think, is setup fine:

CUDAQ[]
(* True *)

CUDAInformation[]
(* {1 -> {"Name" -> "GeForce MX150", "Clock Rate" -> 1037500, 
"Compute Capabilities" -> 6.1, "GPU Overlap" -> 1, 
"Maximum Block Dimensions" -> {1024, 1024, 64}, 
"Maximum Grid Dimensions" -> {2147483647, 65535, 65535}, 
"Maximum Threads Per Block" -> 1024, 
"Maximum Shared Memory Per Block" -> 49152, 
"Total Constant Memory" -> 65536, "Warp Size" -> 32, 
"Maximum Pitch" -> 2147483647, 
"Maximum Registers Per Block" -> 65536, "Texture Alignment" -> 512,
"Multiprocessor Count" -> 3, "Core Count" -> 96, 
"Execution Timeout" -> 1, "Integrated" -> False, 
"Can Map Host Memory" -> True, "Compute Mode" -> "Default", 
"Texture1D Width" -> 131072, "Texture2D Width" -> 131072, 
"Texture2D Height" -> 65536, "Texture3D Width" -> 16384, 
"Texture3D Height" -> 16384, "Texture3D Depth" -> 16384, 
"Texture2D Array Width" -> 32768, 
"Texture2D Array Height" -> 32768, 
"Texture2D Array Slices" -> 2048, "Surface Alignment" -> 512, 
"Concurrent Kernels" -> True, "ECC Enabled" -> False, 
"TCC Enabled" -> False, "Total Memory" -> 2147483648}} *)

CUDADriverVersion[]
(* "430.86" *)

$Version
(* 11.3.0 for Microsoft Windows (64-bit) (March 7, 2018) *)

Any ideas folks? I'd really like to avoid using Matlab ^^. Thanks!