diff --git a/dlib/dnn/core_abstract.h b/dlib/dnn/core_abstract.h
index 53d7e194a..a24c98251 100644
--- a/dlib/dnn/core_abstract.h
+++ b/dlib/dnn/core_abstract.h
@@ -67,6 +67,31 @@ namespace dlib
               (except computes it using a numerically accurate method)
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    bool dnn_prefer_fastest_algorithms(
+    );
+    /*!
+        ensures
+            - If dlib should prefer to use fast algorithms rather than ones that use less
+              RAM then this function returns true and false otherwise.
+            - On program startup this function will default to true.
+    !*/
+
+    void set_dnn_prefer_fastest_algorithms(
+    );
+    /*!
+        ensures
+            - #dnn_prefer_fastest_algorithms() == true
+    !*/
+
+    void set_dnn_prefer_smallest_algorithms(
+    );
+    /*!
+        ensures
+            - #dnn_prefer_fastest_algorithms() == false 
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     template <
diff --git a/dlib/dnn/cudnn_dlibapi.cpp b/dlib/dnn/cudnn_dlibapi.cpp
index ce1cdbae9..9a27d8b4d 100644
--- a/dlib/dnn/cudnn_dlibapi.cpp
+++ b/dlib/dnn/cudnn_dlibapi.cpp
@@ -13,6 +13,7 @@
 #include "cuda_utils.h"
 #include "cpu_dlib.h"
 #include "cuda_dlib.h"
+#include "tensor_tools.h"
 
 static const char* cudnn_get_error_string(cudnnStatus_t s)
 {
@@ -773,7 +774,7 @@ namespace dlib
                         (const cudnnFilterDescriptor_t)filter_handle,
                         (const cudnnConvolutionDescriptor_t)conv_handle,
                         descriptor(dest_desc),
-                        CUDNN_CONVOLUTION_FWD_PREFER_FASTEST, // or CUDNN_CONVOLUTION_FWD_NO_WORKSPACE,
+                        dnn_prefer_fastest_algorithms()?CUDNN_CONVOLUTION_FWD_PREFER_FASTEST:CUDNN_CONVOLUTION_FWD_NO_WORKSPACE,
                         std::numeric_limits<size_t>::max(),
                         &forward_best_algo));
                 forward_algo = forward_best_algo;
@@ -797,7 +798,7 @@ namespace dlib
                         descriptor(dest_desc),
                         (const cudnnConvolutionDescriptor_t)conv_handle,
                         descriptor(data),
-                        CUDNN_CONVOLUTION_BWD_DATA_PREFER_FASTEST,
+                        dnn_prefer_fastest_algorithms()?CUDNN_CONVOLUTION_BWD_DATA_PREFER_FASTEST:CUDNN_CONVOLUTION_BWD_DATA_NO_WORKSPACE,
                         std::numeric_limits<size_t>::max(),
                         &backward_data_best_algo));
                 backward_data_algo = backward_data_best_algo;
@@ -821,7 +822,7 @@ namespace dlib
                         descriptor(dest_desc),
                         (const cudnnConvolutionDescriptor_t)conv_handle,
                         (const cudnnFilterDescriptor_t)filter_handle,
-                        CUDNN_CONVOLUTION_BWD_FILTER_PREFER_FASTEST,
+                        dnn_prefer_fastest_algorithms()?CUDNN_CONVOLUTION_BWD_FILTER_PREFER_FASTEST:CUDNN_CONVOLUTION_BWD_FILTER_NO_WORKSPACE,
                         std::numeric_limits<size_t>::max(),
                         &backward_filters_best_algo));
                 backward_filters_algo = backward_filters_best_algo;
diff --git a/dlib/dnn/tensor_tools.cpp b/dlib/dnn/tensor_tools.cpp
index fa96d1dce..5b72dfa1a 100644
--- a/dlib/dnn/tensor_tools.cpp
+++ b/dlib/dnn/tensor_tools.cpp
@@ -5,6 +5,38 @@
 
 #include "tensor_tools.h"
 #include "../string.h"
+#include <atomic>
+
+namespace dlib
+{
+    namespace
+    {
+        std::atomic<bool>& dnn_prefer_fastest_algo (
+        )
+        {
+            static std::atomic<bool> var(true);
+            return var;
+        }
+    }
+
+    bool dnn_prefer_fastest_algorithms (
+    )
+    {
+        return dnn_prefer_fastest_algo();
+    }
+
+    void set_dnn_prefer_fastest_algorithms(
+    )
+    {
+        dnn_prefer_fastest_algo() = true;
+    }
+
+    void set_dnn_prefer_smallest_algorithms(
+    )
+    {
+        dnn_prefer_fastest_algo() = false;
+    }
+}
 
 namespace dlib { namespace tt
 {
diff --git a/dlib/dnn/tensor_tools.h b/dlib/dnn/tensor_tools.h
index 433dbee5a..4febd3ce6 100644
--- a/dlib/dnn/tensor_tools.h
+++ b/dlib/dnn/tensor_tools.h
@@ -11,6 +11,13 @@
 #include "cuda_dlib.h"
 #include "../rand.h"
 
+namespace dlib
+{
+    bool dnn_prefer_fastest_algorithms();
+    void set_dnn_prefer_fastest_algorithms();
+    void set_dnn_prefer_smallest_algorithms();
+}
+
 namespace dlib { namespace tt
 {