I have almost an identical setup and mine runs at a solid 100%
phenom II black 955 3.2
win7 64
Radeon 4870
I notice a slight difference in our modelines, attached mine for comparison. Disregard the fact that yours chooses 1 and mine select 0, I labelled mine 0-7 instead of 1-8, see below.
crt_range0 15625-16240, 50-65, 3.000, 4.700, 7.700, 0.190, 0.191, 1.018, 0, 0, 192, 248, 0, 0
crt_range1 16029-17200, 50-65, 1.220, 4.728, 7.626, 0.190, 0.191, 1.018, 0, 0, 249, 256, 0, 0
crt_range2 18300-18800, 50-65, 8.300, 2.750, 9.000, 0.190, 0.191, 1.018, 0, 0, 257, 280, 0, 0
crt_range3 18448-31000, 50-65, 6.278, 2.058, 7.410, 0.799, 0.828, .876, 0, 0, 281, 360, 0, 0
crt_range4 24000-29000, 58-65, 1.163, 3.595, 1.798, 0.081, 0.162, 0.889, 0, 0, 376, 384, 0, 0
crt_range5 24000-29000, 57-65, 1.549, 2.820, 6.502, 0.225, 0.150, 2.021, 0, 0, 392, 400, 0, 0
crt_range6 30000-34000, 58-65, 0.636, 3.813, 1.906, 0.020, 0.106, 0.607, 0, 0, 432, 496, 0, 0
crt_range7 33001-38000, 58-65, 0.942, 3.062, 2.827, 0.471, 0.118, 0.972, 0, 0, 512, 588, 0, 0
Both are selecting D3D. Did you update to the newest vmmaker and arcadeosd? When you go into the mame menu does it show it running at 60hz?