Hmmm...how does a high intelligence kill Dagoth Ur fast? Aren't the Blunt Weapon (Sunder) /Short Blade (Keening) skills more important? At the most, he would be able to cast spells non stop.
I took me about a month's playing time to finally kill Mr Ur. In the end, it was because I had a companion (from the Morrowind Comes Alive: Recruitable NPCS mod). I got a female Vampire to be my companion (and more).
[Dramatisation] I raised Keening to strike the Heart as many times as I could as Dagoth Ur ran towards me shouting "FOOL! WHAT ARE YOU DOING?!". With one mighting swing, he landed a near fatal blow. Desperate to stay alive, I gulped down 3 Restore Health potions and quickly cast my Hoptoad spell - in the nick of time! As Dagoth Ur raised his hand for a final blow, I lept over his head on to the bridge, stumbling my way away from him. Out of the corner of my eye, I saw Mirear (my companion) rush in to engage Dagoth Ur, determined to protect my life.
Enraged, Dagoth Ur landed hit after hit on Mirear, causing her to cry out in pain. Disoriented by the flurry of blows she received, she could hardly retaliate. As I watched on, I realised that she never had the intention of retaliation....the Heart was still intact! There was no way of hurting Dagoth Ur as long as he is still able to draw divine energies from the Heart. Consumed with the fear of both Dagoth Ur and the fear of losing Mirear, I sat dumbfounded as Mirear continued to receive blows that would have killed a normal Bosmer many times over. My strength seemed to leave me as my bow slowly slipped from my hands...
Time seemed to slow down...the sound of Mirear's screams, the heat from the boiling lava beneath, the stench of the foul air within the Facility Cavern...I continued to stare blankly at Mirear. The last blow from Dagoth Ur shattered her right glass pauldron, sending pieces of glass, glittering red from the lava below us, flying, as if in slow motion, across her face. The largest piece scratched her face in its flight as she turn towards me. My eyes met hers. Tears began to form in both our eyes...is this how it would end? Is this how, after such a long struggle, I would lose both my love and my pride in this Azura forsaken place?
No......no.....NO!!!!
Tears streaked down my dirt covered face. As the Bow of Shadows fell from my right hand, my left wrapped itself around Keening. In a anguish driven craze, I flung my body towards the Heart using my entire body weight to plunge Keening straight through it's pulsating walls. A blinding light exploded from Heart as it dispersed with a forceful, omnidirectional blast, knocking all three of us off our feet. As our eyes readjusted themselves back to the dimly lit Facility Cavern, I looked up and saw Mirear struggling to get up beside the motionless body of Dagoth Ur. When my vision cleared, a smile emerged from my face....there lies Dagoth Ur, with Mirear's Daedric Short Blade of Leeching firmly embedded in his chest. The health absorption abilities of that blade has kept Mirear alive...down to it's very last charge.
It was over. I stumbled towards Mirear and hugged her as the both of us wept tears of relieve, our soft sobs echoing across the walls of the Facility Cavern. [/Dramatisation]