diff --git a/modules/processing.py b/modules/processing.py
index 29a3743f5..b75f25157 100644
--- a/modules/processing.py
+++ b/modules/processing.py
@@ -13,7 +13,7 @@ from skimage import exposure
 from typing import Any, Dict, List
 
 import modules.sd_hijack
-from modules import devices, prompt_parser, masking, sd_samplers, lowvram, generation_parameters_copypaste, extra_networks, sd_vae_approx, scripts, sd_samplers_common
+from modules import devices, prompt_parser, masking, sd_samplers, lowvram, generation_parameters_copypaste, extra_networks, sd_vae_approx, scripts, sd_samplers_common, sd_unet
 from modules.sd_hijack import model_hijack
 from modules.shared import opts, cmd_opts, state
 import modules.shared as shared
@@ -674,6 +674,8 @@ def process_images_inner(p: StableDiffusionProcessing) -> Processed:
             if shared.opts.live_previews_enable and opts.show_progress_type == "Approx NN":
                 sd_vae_approx.model()
 
+            sd_unet.apply_unet()
+
         if state.job_count == -1:
             state.job_count = p.n_iter
 
diff --git a/modules/script_callbacks.py b/modules/script_callbacks.py
index 40f388a59..d2728e12c 100644
--- a/modules/script_callbacks.py
+++ b/modules/script_callbacks.py
@@ -111,6 +111,7 @@ callback_map = dict(
     callbacks_before_ui=[],
     callbacks_on_reload=[],
     callbacks_list_optimizers=[],
+    callbacks_list_unets=[],
 )
 
 
@@ -271,6 +272,18 @@ def list_optimizers_callback():
     return res
 
 
+def list_unets_callback():
+    res = []
+
+    for c in callback_map['callbacks_list_unets']:
+        try:
+            c.callback(res)
+        except Exception:
+            report_exception(c, 'list_unets')
+
+    return res
+
+
 def add_callback(callbacks, fun):
     stack = [x for x in inspect.stack() if x.filename != __file__]
     filename = stack[0].filename if len(stack) > 0 else 'unknown file'
@@ -430,3 +443,10 @@ def on_list_optimizers(callback):
     to it."""
 
     add_callback(callback_map['callbacks_list_optimizers'], callback)
+
+
+def on_list_unets(callback):
+    """register a function to be called when UI is making a list of alternative options for unet.
+    The function will be called with one argument, a list, and shall add objects of type modules.sd_unet.SdUnetOption to it."""
+
+    add_callback(callback_map['callbacks_list_unets'], callback)
diff --git a/modules/sd_hijack.py b/modules/sd_hijack.py
index f93df0a63..487dfd600 100644
--- a/modules/sd_hijack.py
+++ b/modules/sd_hijack.py
@@ -3,7 +3,7 @@ from torch.nn.functional import silu
 from types import MethodType
 
 import modules.textual_inversion.textual_inversion
-from modules import devices, sd_hijack_optimizations, shared, script_callbacks, errors
+from modules import devices, sd_hijack_optimizations, shared, script_callbacks, errors, sd_unet
 from modules.hypernetworks import hypernetwork
 from modules.shared import cmd_opts
 from modules import sd_hijack_clip, sd_hijack_open_clip, sd_hijack_unet, sd_hijack_xlmr, xlmr
@@ -43,7 +43,7 @@ def list_optimizers():
     optimizers.extend(new_optimizers)
 
 
-def apply_optimizations():
+def apply_optimizations(option=None):
     global current_optimizer
 
     undo_optimizations()
@@ -60,7 +60,7 @@ def apply_optimizations():
         current_optimizer.undo()
         current_optimizer = None
 
-    selection = shared.opts.cross_attention_optimization
+    selection = option or shared.opts.cross_attention_optimization
     if selection == "Automatic" and len(optimizers) > 0:
         matching_optimizer = next(iter([x for x in optimizers if x.cmd_opt and getattr(shared.cmd_opts, x.cmd_opt, False)]), optimizers[0])
     else:
@@ -72,12 +72,13 @@ def apply_optimizations():
         matching_optimizer = optimizers[0]
 
     if matching_optimizer is not None:
-        print(f"Applying optimization: {matching_optimizer.name}... ", end='')
+        print(f"Applying attention optimization: {matching_optimizer.name}... ", end='')
         matching_optimizer.apply()
         print("done.")
         current_optimizer = matching_optimizer
         return current_optimizer.name
     else:
+        print("Disabling attention optimization")
         return ''
 
 
@@ -155,9 +156,9 @@ class StableDiffusionModelHijack:
     def __init__(self):
         self.embedding_db.add_embedding_dir(cmd_opts.embeddings_dir)
 
-    def apply_optimizations(self):
+    def apply_optimizations(self, option=None):
         try:
-            self.optimization_method = apply_optimizations()
+            self.optimization_method = apply_optimizations(option)
         except Exception as e:
             errors.display(e, "applying cross attention optimization")
             undo_optimizations()
@@ -194,6 +195,11 @@ class StableDiffusionModelHijack:
 
         self.layers = flatten(m)
 
+        if not hasattr(ldm.modules.diffusionmodules.openaimodel, 'copy_of_UNetModel_forward_for_webui'):
+            ldm.modules.diffusionmodules.openaimodel.copy_of_UNetModel_forward_for_webui = ldm.modules.diffusionmodules.openaimodel.UNetModel.forward
+
+        ldm.modules.diffusionmodules.openaimodel.UNetModel.forward = sd_unet.UNetModel_forward
+
     def undo_hijack(self, m):
         if type(m.cond_stage_model) == xlmr.BertSeriesModelWithTransformation:
             m.cond_stage_model = m.cond_stage_model.wrapped
@@ -215,6 +221,8 @@ class StableDiffusionModelHijack:
         self.layers = None
         self.clip = None
 
+        ldm.modules.diffusionmodules.openaimodel.UNetModel.forward = ldm.modules.diffusionmodules.openaimodel.copy_of_UNetModel_forward_for_webui
+
     def apply_circular(self, enable):
         if self.circular_enabled == enable:
             return
diff --git a/modules/sd_models.py b/modules/sd_models.py
index 91b3eb115..835bc016e 100644
--- a/modules/sd_models.py
+++ b/modules/sd_models.py
@@ -14,7 +14,7 @@ import ldm.modules.midas as midas
 
 from ldm.util import instantiate_from_config
 
-from modules import paths, shared, modelloader, devices, script_callbacks, sd_vae, sd_disable_initialization, errors, hashes, sd_models_config
+from modules import paths, shared, modelloader, devices, script_callbacks, sd_vae, sd_disable_initialization, errors, hashes, sd_models_config, sd_unet
 from modules.sd_hijack_inpainting import do_inpainting_hijack
 from modules.timer import Timer
 import tomesd
@@ -532,6 +532,8 @@ def reload_model_weights(sd_model=None, info=None):
         if sd_model.sd_model_checkpoint == checkpoint_info.filename:
             return
 
+        sd_unet.apply_unet("None")
+
         if shared.cmd_opts.lowvram or shared.cmd_opts.medvram:
             lowvram.send_everything_to_cpu()
         else:
diff --git a/modules/sd_unet.py b/modules/sd_unet.py
new file mode 100644
index 000000000..6d708ad29
--- /dev/null
+++ b/modules/sd_unet.py
@@ -0,0 +1,92 @@
+import torch.nn
+import ldm.modules.diffusionmodules.openaimodel
+
+from modules import script_callbacks, shared, devices
+
+unet_options = []
+current_unet_option = None
+current_unet = None
+
+
+def list_unets():
+    new_unets = script_callbacks.list_unets_callback()
+
+    unet_options.clear()
+    unet_options.extend(new_unets)
+
+
+def get_unet_option(option=None):
+    option = option or shared.opts.sd_unet
+
+    if option == "None":
+        return None
+
+    if option == "Automatic":
+        name = shared.sd_model.sd_checkpoint_info.model_name
+
+        options = [x for x in unet_options if x.model_name == name]
+
+        option = options[0].label if options else "None"
+
+    return next(iter([x for x in unet_options if x.label == option]), None)
+
+
+def apply_unet(option=None):
+    global current_unet_option
+    global current_unet
+
+    new_option = get_unet_option(option)
+    if new_option == current_unet_option:
+        return
+
+    if current_unet is not None:
+        print(f"Dectivating unet: {current_unet.option.label}")
+        current_unet.deactivate()
+
+    current_unet_option = new_option
+    if current_unet_option is None:
+        current_unet = None
+
+        if not (shared.cmd_opts.lowvram or shared.cmd_opts.medvram):
+            shared.sd_model.model.diffusion_model.to(devices.device)
+
+        return
+
+    shared.sd_model.model.diffusion_model.to(devices.cpu)
+    devices.torch_gc()
+
+    current_unet = current_unet_option.create_unet()
+    current_unet.option = current_unet_option
+    print(f"Activating unet: {current_unet.option.label}")
+    current_unet.activate()
+
+
+class SdUnetOption:
+    model_name = None
+    """name of related checkpoint - this option will be selected automatically for unet if the name of checkpoint matches this"""
+
+    label = None
+    """name of the unet in UI"""
+
+    def create_unet(self):
+        """returns SdUnet object to be used as a Unet instead of built-in unet when making pictures"""
+        raise NotImplementedError()
+
+
+class SdUnet(torch.nn.Module):
+    def forward(self, x, timesteps, context, *args, **kwargs):
+        raise NotImplementedError()
+
+    def activate(self):
+        pass
+
+    def deactivate(self):
+        pass
+
+
+def UNetModel_forward(self, x, timesteps=None, context=None, *args, **kwargs):
+    if current_unet is not None:
+        return current_unet.forward(x, timesteps, context, *args, **kwargs)
+
+    return ldm.modules.diffusionmodules.openaimodel.copy_of_UNetModel_forward_for_webui(self, x, timesteps, context, *args, **kwargs)
+
diff --git a/modules/shared.py b/modules/shared.py
index 0897f937a..a5e7824ab 100644
--- a/modules/shared.py
+++ b/modules/shared.py
@@ -403,6 +403,7 @@ options_templates.update(options_section(('sd', "Stable Diffusion"), {
     "sd_vae_checkpoint_cache": OptionInfo(0, "VAE Checkpoints to cache in RAM", gr.Slider, {"minimum": 0, "maximum": 10, "step": 1}),
     "sd_vae": OptionInfo("Automatic", "SD VAE", gr.Dropdown, lambda: {"choices": shared_items.sd_vae_items()}, refresh=shared_items.refresh_vae_list).info("choose VAE model: Automatic = use one with same filename as checkpoint; None = use VAE from checkpoint"),
     "sd_vae_as_default": OptionInfo(True, "Ignore selected VAE for stable diffusion checkpoints that have their own .vae.pt next to them"),
+    "sd_unet": OptionInfo("Automatic", "SD Unet", gr.Dropdown, lambda: {"choices": shared_items.sd_unet_items()}, refresh=shared_items.refresh_unet_list).info("choose Unet model: Automatic = use one with same filename as checkpoint; None = use Unet from checkpoint"),
     "inpainting_mask_weight": OptionInfo(1.0, "Inpainting conditioning mask strength", gr.Slider, {"minimum": 0.0, "maximum": 1.0, "step": 0.01}),
     "initial_noise_multiplier": OptionInfo(1.0, "Noise multiplier for img2img", gr.Slider, {"minimum": 0.5, "maximum": 1.5, "step": 0.01}),
     "img2img_color_correction": OptionInfo(False, "Apply color correction to img2img results to match original colors."),
diff --git a/modules/shared_items.py b/modules/shared_items.py
index 2a8713c87..7f306a06f 100644
--- a/modules/shared_items.py
+++ b/modules/shared_items.py
@@ -29,3 +29,14 @@ def cross_attention_optimizations():
     return ["Automatic"] + [x.title() for x in modules.sd_hijack.optimizers] + ["None"]
 
 
+def sd_unet_items():
+    import modules.sd_unet
+
+    return ["Automatic"] + [x.label for x in modules.sd_unet.unet_options] + ["None"]
+
+
+def refresh_unet_list():
+    import modules.sd_unet
+
+    modules.sd_unet.list_unets()
+
diff --git a/webui.py b/webui.py
index f9210f41b..1e3ff0615 100644
--- a/webui.py
+++ b/webui.py
@@ -58,6 +58,7 @@ import modules.sd_hijack
 import modules.sd_hijack_optimizations
 import modules.sd_models
 import modules.sd_vae
+import modules.sd_unet
 import modules.txt2img
 import modules.script_callbacks
 import modules.textual_inversion.textual_inversion
@@ -291,6 +292,9 @@ def initialize_rest(*, reload_script_modules=False):
     modules.sd_hijack.list_optimizers()
     startup_timer.record("scripts list_optimizers")
 
+    modules.sd_unet.list_unets()
+    startup_timer.record("scripts list_unets")
+
     def load_model():
         """
         Accesses shared.sd_model property to load model.