It depends on whether they're running at a lower data rate due to the low signal power (which leads to low SNR, reducing channel capacity) or if it's just the speed of light delay.
In the former case, a relay could help quite significantly.
In the latter case, it would just add even more delay.
There isn't enough throughput to achieve a negative delay which offsets the actual flight of light time to reach the object. The ratio of throughput delay to actual light delay is so infinitesimal it might as well be zero.
No, the issue is that the throughput is so low with these very small signal strengths that transferring a meaningful amount of data will result in large delays on that side as well. Speed of light isn't the only thing causing measurable latency.
In the former case, a relay could help quite significantly.
In the latter case, it would just add even more delay.