diff --git a/extern/imgui_software_renderer/imgui_sw.cpp b/extern/imgui_software_renderer/imgui_sw.cpp
index 4240ac4d3..ccd9e6eed 100644
--- a/extern/imgui_software_renderer/imgui_sw.cpp
+++ b/extern/imgui_software_renderer/imgui_sw.cpp
@@ -147,7 +147,7 @@ inline ImU32 color_convert_float4_to_u32(const ImVec4 &in)
 // TODO: make it 32-bit or else
 
 using Int = int32_t;
-const Int kFixedBias = 256;
+const Int kFixedBias = 1;
 
 struct Point
 {
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 0c4c43b44..0f9353cb8 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -6296,6 +6296,17 @@ bool FurnaceGUI::loop() {
     }
 #endif
 
+    if (settings.displayRenderTime) {
+      String renderTime=fmt::sprintf("%.0fµs",ImGui::GetIO().DeltaTime*1000000.0);
+      String renderTime2=fmt::sprintf("%.1f FPS",1.0/ImGui::GetIO().DeltaTime);
+      ImDrawList* dl=ImGui::GetForegroundDrawList();
+      ImVec2 markPos=ImVec2(canvasW-ImGui::CalcTextSize(renderTime.c_str()).x-60.0*dpiScale,4.0*dpiScale);
+      ImVec2 markPos2=ImVec2(canvasW-ImGui::CalcTextSize(renderTime2.c_str()).x-160.0*dpiScale,4.0*dpiScale);
+
+      dl->AddText(markPos,0xffffffff,renderTime.c_str());
+      dl->AddText(markPos2,0xffffffff,renderTime2.c_str());
+    }
+
     layoutTimeEnd=SDL_GetPerformanceCounter();
 
     // backup trigger
diff --git a/src/gui/gui.h b/src/gui/gui.h
index f885b7d2b..bd286e6c9 100644
--- a/src/gui/gui.h
+++ b/src/gui/gui.h
@@ -1842,6 +1842,7 @@ class FurnaceGUI {
     int cursorWheelStep;
     int vsync;
     int frameRateLimit;
+    int displayRenderTime;
     unsigned int maxUndoSteps;
     String mainFontPath;
     String headFontPath;
@@ -2073,6 +2074,7 @@ class FurnaceGUI {
       cursorWheelStep(0),
       vsync(1),
       frameRateLimit(60),
+      displayRenderTime(0),
       maxUndoSteps(100),
       mainFontPath(""),
       headFontPath(""),
diff --git a/src/gui/osc.cpp b/src/gui/osc.cpp
index a70d244a7..7af0bce24 100644
--- a/src/gui/osc.cpp
+++ b/src/gui/osc.cpp
@@ -216,15 +216,23 @@ void FurnaceGUI::drawOsc() {
     ImU32 guideColor=ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_GUIDE]);
     ImGui::ItemSize(size,style.FramePadding.y);
     if (ImGui::ItemAdd(rect,ImGui::GetID("wsDisplay"))) {
-      dl->AddRectFilledMultiColor(
-        inRect.Min,
-        inRect.Max,
-        ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG1]),
-        ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG2]),
-        ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG4]),
-        ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG3]),
-        settings.oscRoundedCorners?(8.0f*dpiScale):0.0f
-      );
+      if (safeMode || renderBackend==GUI_BACKEND_SOFTWARE) {
+        dl->AddRectFilled(
+          inRect.Min,
+          inRect.Max,
+          ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG4])
+        );
+      } else {
+        dl->AddRectFilledMultiColor(
+          inRect.Min,
+          inRect.Max,
+          ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG1]),
+          ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG2]),
+          ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG4]),
+          ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_BG3]),
+          settings.oscRoundedCorners?(8.0f*dpiScale):0.0f
+        );
+      }
 
       dl->AddLine(
         ImLerp(rect.Min,rect.Max,ImVec2(0.0f,0.5f)),
@@ -367,7 +375,7 @@ void FurnaceGUI::drawOsc() {
       dl->Flags=prevFlags;
       
       if (settings.oscBorder) {
-        dl->AddRect(inRect.Min,inRect.Max,borderColor,settings.oscRoundedCorners?(8.0f*dpiScale):0.0f,0,1.5f*dpiScale);
+        dl->AddRect(inRect.Min,inRect.Max,borderColor,(settings.oscRoundedCorners && !(safeMode || renderBackend==GUI_BACKEND_SOFTWARE))?(8.0f*dpiScale):0.0f,0,1.5f*dpiScale);
       }
     }
     if (oscZoomSlider && ImGui::IsItemHovered()) {
diff --git a/src/gui/settings.cpp b/src/gui/settings.cpp
index 4a01c8513..b63c29c0e 100644
--- a/src/gui/settings.cpp
+++ b/src/gui/settings.cpp
@@ -476,6 +476,12 @@ void FurnaceGUI::drawSettings() {
           ImGui::SetTooltip("only applies when VSync is disabled.");
         }
 
+        bool displayRenderTimeB=settings.displayRenderTime;
+        if (ImGui::Checkbox("Display render time",&displayRenderTimeB)) {
+          settings.displayRenderTime=displayRenderTimeB;
+          settingsChanged=true;
+        }
+
         bool renderClearPosB=settings.renderClearPos;
         if (ImGui::Checkbox("Late render clear",&renderClearPosB)) {
           settings.renderClearPos=renderClearPosB;
@@ -4006,6 +4012,7 @@ void FurnaceGUI::readConfig(DivConfig& conf, FurnaceGUISettingGroups groups) {
 
     settings.vsync=conf.getInt("vsync",1);
     settings.frameRateLimit=conf.getInt("frameRateLimit",100);
+    settings.displayRenderTime=conf.getInt("displayRenderTime",0);
 
     settings.chanOscThreads=conf.getInt("chanOscThreads",0);
     settings.renderPoolThreads=conf.getInt("renderPoolThreads",0);
@@ -4512,6 +4519,7 @@ void FurnaceGUI::readConfig(DivConfig& conf, FurnaceGUISettingGroups groups) {
   clampSetting(settings.cursorWheelStep,0,1);
   clampSetting(settings.vsync,0,4);
   clampSetting(settings.frameRateLimit,0,1000);
+  clampSetting(settings.displayRenderTime,0,1);
 
   if (settings.exportLoops<0.0) settings.exportLoops=0.0;
   if (settings.exportFadeOut<0.0) settings.exportFadeOut=0.0;  
@@ -4537,6 +4545,7 @@ void FurnaceGUI::writeConfig(DivConfig& conf, FurnaceGUISettingGroups groups) {
 
     conf.set("vsync",settings.vsync);
     conf.set("frameRateLimit",settings.frameRateLimit);
+    conf.set("displayRenderTime",settings.displayRenderTime);
 
     conf.set("chanOscThreads",settings.chanOscThreads);
     conf.set("renderPoolThreads",settings.renderPoolThreads);
@@ -5531,6 +5540,10 @@ void FurnaceGUI::applyUISettings(bool updateFonts) {
     sty.FrameRounding=0.0f;
     sty.GrabRounding=0.0f;
     sty.FrameShading=0.0f;
+    sty.TabRounding=0.0f;
+    sty.ScrollbarRounding=0.0f;
+    sty.ChildRounding=0.0f;
+    sty.PopupRounding=0.0f;
     sty.AntiAliasedLines=false;
     sty.AntiAliasedLinesUseTex=false;
     sty.AntiAliasedFill=false;