move some settings to the new Optimization page

add slider for token merging for img2img
rework StableDiffusionProcessing to have the token_merging_ratio field
fix a bug with applying png optimizations for live previews when they shouldn't be applied

modules/sd_models.py

@@ -583,23 +583,27 @@ def unload_model_weights(sd_model=None, info=None):
     return sd_model
 
 
-def apply_token_merging(sd_model, hr: bool):
+def apply_token_merging(sd_model, token_merging_ratio):
     """
     Applies speed and memory optimizations from tomesd.
-
-    Args:
-        hr (bool): True if called in the context of a high-res pass
     """
 
-    ratio = shared.opts.token_merging_ratio
-    if hr:
-        ratio = shared.opts.token_merging_ratio_hr
+    current_token_merging_ratio = getattr(sd_model, 'applied_token_merged_ratio', 0)
 
-    tomesd.apply_patch(
-        sd_model,
-        ratio=ratio,
-        use_rand=False,  # can cause issues with some samplers
-        merge_attn=True,
-        merge_crossattn=False,
-        merge_mlp=False
-    )
+    if current_token_merging_ratio == token_merging_ratio:
+        return
+
+    if current_token_merging_ratio > 0:
+        tomesd.remove_patch(sd_model)
+
+    if token_merging_ratio > 0:
+        tomesd.apply_patch(
+            sd_model,
+            ratio=token_merging_ratio,
+            use_rand=False,  # can cause issues with some samplers
+            merge_attn=True,
+            merge_crossattn=False,
+            merge_mlp=False
+        )
+
+    sd_model.applied_token_merged_ratio = token_merging_ratio