Sensor

Just like the M65 RGB Elite, the Ironclaw RGB uses the PixArt PMW3391. It's an absolutely high-end optical sensor; it's raw, responsive, and pinpoint-accurate with a ridiculously high perfect control speed. I had no spin-outs or any errors while playing high-paced FPS games with the mouse, but there are some quirks I detected with my testing methods.

The specifications of this sensor are nearly identical to the PMW3389. Nominal acceleration and maximum tracking speed values are 50 G and 400 IPS (10.16 m/s). You can set the resolution from 100 to 18,000 in steps of 1 CPI—this is unique as up until now, the lowest step was 50. The available polling rates are 125, 250, 500, and 1000, which translates into nominal response times of 8 ms, 4 ms, 2 ms, and 1 ms. The default lift-off distance was pretty high (as the mouse is calibrated for Corsair pads), but with the surface calibration in the software, I could bring it down to below 1 DVD in height.

Paint Test

There is no jitter on the reasonable CPI steps, or unwanted angle snapping (you can turn this on in the software, but I would highly advise against it) and sensor lens rattle.

CPI Divergence

CPI divergence on the Ironclaw RGB is average, but gets rather high by the time it reaches 5000 CPI. Please note that this test may not completely represent reality, but is generally accurate enough to show anomalies.

Perfect Control Speed

Perfect control speed is very high on the PMW3391—there is no way of hitting this value while gaming, even with incredibly low in-game sensitivity. The nominal perfect control speed is 400 IPS, which translates to about 10.16 meters per second. The PCS values don't correlate with the set resolution, which means 100 and 18,000 CPI both hit their limits at about the same value.

Speed Related Accuracy Variance

This test shows the sensor's accuracy at different speeds. You can see me doing a fast swipe to the right before I slowly slide the mouse back to its original position. There is no acceleration or deceleration; any displacement in this test is almost entirely caused by human error.

Polling Rate

All polling rate values seem normal. There are no suspicious periodic drops or other sorts of outliers. At 1000 Hz, there are some high spikes, but all my mice tend to have them on the latest Windows 10 versions, on all the mouse pads I own. This is strange, but I have found no fix for it. It doesn't really seem to affect anything in game.

Input Lag & Smoothing

There are some very strange kinks in the count graphs, which represent a single swipe towards the right. These happen to be there on all CPI steps and polling-rate values. It didn't seem to affect my in-game performance, but it was hard to tell because the mouse didn't really fit my hands.
There is no input lag or any detectable smoothing until 2000 CPI. Right above that value, some smoothing turns on, resulting in about +2 ms input lag. This value correlates with certain CPI steps and reaches +10 ms with 18,000 CPI. The M65 RGB Elite uses the exact same sensor, but doesn't seem to have any input lag on any CPI level, so I'm going to assume this issue is firmware-related. Most PMW3389-equipped mice act the same way, and I don't think this is much of an issue. I would definitely recommend staying below 2000 CPI if you are playing competitively, but the +2 ms is negligible otherwise. I've let Corsair know of the problem, and hopefully, a quick firmware update will fix this.

Click Latency

The click latency is roughly +2.6 ms compared to the SteelSeries Ikari, which is considered as a baseline with 0 ms. The data comes from this thread and my own testings. Testing was done with a Logitech G102 and the Ironclaw, using qsxcv's program.