Это не займет много времени, если вы работаете с массивом, а не с рабочим листом.
dim dt as long, i as long, j as long, tmp as variant, arr as variant
dt = dateserial(2019, 1, 3)
with worksheets("sheet1")
tmp = .range(.cells(1, "A"), .cells(.rows.count, "A").end(xlup)).value2
end with
redim arr(0)
for i=lbound(tmp, 1) to ubound(tmp, 1)
if tmp(i, 1) = dt then
redim preserve arr(j)
arr(j) = i 'collect row numbers
j=j+1
end if
next i
for i=lbound(arr) to ubound(arr)
debug.print arr(i) 'print row numbers
next i