According to the Church tradition, the suffering of Purgatory is intense.
Dante in the Divine Comedy, Purgatorio states: "Once in the fire, I would have gladly jumped into the depths of boiling glass to find relief from the intensity of heat." (Canto XXVII. 51).
In the revelation to St. Faustina, Christ said to her: "Oh, if you only knew the torments they suffer, you would continually offer for them the alms of the spirit and pay off the debt to My justice."
St. Catherine of Genoa says that when the soul leaves the body, realizing its imperfections, it casts itself willingly into Purgatory. These souls cannot have self-centered thoughts such as regrets, or think, "that soul will leave before me", etc. They see only the working of divine goodness and mercy.
As they are being purified, their love of God increases along with their sufferings because they desire God evermore. Only their time is shortened.
Although they suffer greatly, they do not consider it as such, so happy are they to be on their way to encounter the living God. See Treatise on Purgatory.
Purgatory is in the nature of things, the Great Purity of God's Essence and the human soul disfigured by Sin and the punishment to sin in justice stand in contradiction to one another.
Purgatory is not so much the punishment for sin but an active realization in human souls of God's Great Mercy and Justice clearing the way to God's vision of glory.
What is the straight way to heaven?
Besides dying as a child after baptism and without stain of sin, the other sure way is through martyrdom. A good example of this is the good thief.
One of the criminals hanging in crucifixion blasphemed him: "Aren't you the Messiah? Then save yourself and us."
But the other one rebuked him: "Have you no fear of God, seeing that you are under the same sentence? We deserve it, after all. We are only paying the price for what we've done wrong."
And Jesus replied, "I assure you: this day you will be with me in paradise." The good thief admitted his sins and was willing to accept the suffering of crucifixion and so gained heaven.
"I hasten to the other world, to God alone,
Into the incomprehensible light, the very fire of love..." (Sr. Faustina)