From GTA BOOM: “In his 100% speedrun, ToriksLV managed to finish the game in 10 hours, 15 minutes and 44 seconds, beating the previous record of 10 hours, 29 minutes and 33 seconds. In that time, he completed absolutely everything there is to complete in GTA 5’s single-player mode. All the spaceship parts, all the side missions, everything.”
Source: N4G PC GTA 5 Story Mode Speedrunning Record Set At 10 Hours