試試看，我覺得應該可以快很多。

Sub 效率總表G欄空白填上資料()
    Dim i as long, j As long
    dim a(2 to 32000, 0) as variant
    
    For i = 2 To 32000
        For j = 2 To 32000
            With Worksheets("Page1")
                If .Cells(i, "G") = "" And .Cells(i, "I") <> "全檢" _
And .Cells(i, "F") = Worksheets("標準工時表").Cells(j, "F") Then
                a(i, 0) = Worksheets("標準工時表").Cells(j, "K")
                End If
            end with
        Next j
    Next i
    
    worksheets("Page1").range("G2:G32000") = a
End Sub

從giulian的程式再修改

先做If檢核，以避免落入J迴圈

Sub 效率總表G欄空白填上資料()
    Dim i as long, j As long
    Dim a(2 to 32000, 0) as variant
    
    With Worksheets("Page1")
        For i = 2 To 32000
            If .Cells(i, "G") = "" And .Cells(i, "I") <> "全檢" Then
                For j = 2 To 32000
                If .Cells(i, "F") = Worksheets("標準工時表").Cells(j, "F") Then
                    a(i, 0) = Worksheets("標準工時表").Cells(j, "K")
                End If
                Next j
            End if
        Next i
    
        .range("G2:G32000") = a
    End With
End Sub

不更動原始資料或程式設計架構的話
簡化的方法就是「Exit For」

不管原因或者合理性
單純就程式碼來看

要的是「符合條件的最後一筆」的資料
就沒必要從前面每筆找，每筆判斷，每筆換然後再被後面的蓋掉值
那就改成從後面找回來，一找到就結束

Sub 效率總表G欄空白填上資料()
    Application.ScreenUpdating = False
    Dim i, j As Integer

    For i = 2 To 32000
        For j = 32000 To 2 Step -1

            If Worksheets("Page1").Cells(i, "G") = "" And Worksheets("Page1").Cells(i, "I") <> "全檢" And Worksheets("Page1").Cells(i, "F") = Worksheets("標準工時表").Cells(j, "F") Then 
                Worksheets("Page1").Cells(i, "G") = Worksheets("標準工時表").Cells(j, "K")
                Exit For  '只要有值就離開這層迴圈
            End If
        Next
    Next

    Application.ScreenUpdating = True
End Sub

萬一要的是「符合條件的第一筆」的資料
那就改成

Sub 效率總表G欄空白填上資料()
    Application.ScreenUpdating = False
    Dim i, j As Integer

    For i = 2 To 32000
        For j = 2 To 32000

            If Worksheets("Page1").Cells(i, "G") = "" And Worksheets("Page1").Cells(i, "I") <> "全檢" And Worksheets("Page1").Cells(i, "F") = Worksheets("標準工時表").Cells(j, "F") Then 
                Worksheets("Page1").Cells(i, "G") = Worksheets("標準工時表").Cells(j, "K")
                Exit For  '只要有值就離開這層迴圈
            End If
        Next
    Next

    Application.ScreenUpdating = True
End Sub

原始程式迴圈總共要跑 32,000x32,000 = 1,024,000,000
10億次
一級戒備，膽子真大(Quote by 寒戰 保安局長陸明華)

其實你仔細思考細節就會知道怎麼做，借用pcw的代碼

Sub 效率總表G欄空白填上資料()
Dim i as long, j As long
dim a(2 to 32000, 0) as variant
dim G,I,F

For i = 2 To 32000
    這邊先設變數把這一輪要用到的丟進去,這樣做是避免每一輪都要重新讓應用程式再去找出這些資料
       G=Worksheets("Page1").Cells(i, "G")
       I=Worksheets("Page1").Cells(i, "I")
       F=Worksheets("Page1").Cells(i, "F") 
   
   For j = 2 To 32000
              這邊會建議先檢查一個關鍵的就好，不用每個都測，
              如果筆數少感覺不出來差別但你的狀況會差很多
              IF F= Worksheets("標準工時表").Cells(j, "F")  then
                  這裡在做最後判斷
                If G="" And I<> "全檢" And Then
                    a(i, 0) = Worksheets("標準工時表").Cells(j, "K")
                End If
              end if
    Next j
Next i

worksheets("Page1").range("G2:G32000") = a

End Sub