perf(segmentation): make segmentation read 3x faster (#3577)

extensions/cornerstone-dicom-seg/src/viewports/OHIFCornerstoneSEGViewport.tsx

@@ -317,7 +317,6 @@ function OHIFCornerstoneSEGViewport(props) {
 
     setIsHydrated(isHydrated);
   };
-
   return (
     <>
       <ViewportActionBar
@@ -344,10 +343,13 @@ function OHIFCornerstoneSEGViewport(props) {
             patientSex: PatientSex || '',
             patientAge: PatientAge || '',
             MRN: PatientID || '',
-            thickness: SliceThickness ? `${parseFloat(SliceThickness).toFixed(2)}mm` : '',
+            thickness: SliceThickness
+              ? utils.roundNumber(SliceThickness, 2)
+              : '',
+            thicknessUnits: SliceThickness !== undefined ? 'mm' : '',
             spacing:
               SpacingBetweenSlices !== undefined
-                ? `${parseFloat(SpacingBetweenSlices).toFixed(2)}mm`
+                ? utils.roundNumber(SpacingBetweenSlices, 2)
                 : '',
             scanner: ManufacturerModelName || '',
           },