Glass fiber-reinforced polymer (GFRP) composites are widely used in engineering applications due to their high strength-to-weight ratio and corrosion resistance. However, drilling at high feed rates induces transient, quasi-impact loading with severe stress concentrations, exacerbating delamination at hole entry and exit. This experimental study comprehensively investigates the effects of feed rate, spindle speed, drill geometry and diameter, pre-drilling, and cooling on the delamination factor of 2-mm-thick GFRP laminates. Infrared thermography was employed to capture localized surface temperature distributions, and drill-induced failure mechanisms were comparatively evaluated against low-velocity impact tests. The results revealed that increasing the feed rate substantially elevated the delamination factor due to abrupt dynamic thrust forces. Among all tools, the 10-mm step drill minimized delamination by progressively distributing axial loads, while pre-drilling mitigated initial penetration severity. Thermographic analysis showed that higher spindle speeds raised cutting temperatures, whereas cooling effectively suppressed matrix thermal softening, thereby reducing delamination. In low-velocity impact tests, the damaged areas for flat, hemispherical, and conical impactors were 0.20, 1.21, and 3.19〖" cm" 〗^2, respectively, confirming that sharp contact geometries induce severe localized damage analogous to high feed-rate drilling. Consequently, controlling feed rate, employing step drills, pre-drilling, and applying cooling are critical strategies to suppress delamination in GFRP composite drilling.