Objection 1. It would seem that not all merits and demerits, one's own as well as those of others, will be seen by anyone at a single glance. For things considered singly are not seen at one glance. Now the damned will consider their sins singly and will bewail them, wherefore they say (Wisdom 5:8): "What hath pride profited us?" Therefore they will not see them all at a glance.
Objection 2. Further, the Philosopher says (Topic. ii) that "we do not arrive at understanding several things at the same time." Now merits and demerits, both our own and those of others, will not be visible save to the intellect. Therefore it will be impossible for them all to be seen at the same time.
Objection 3. Further, the intellect of the damned after the resurrection will not be clearer than the intellect of the blessed and of the angels is now, as to the natural knowledge whereby they know things by innate species. Now by such knowledge the angels do not see several things at the same time. Therefore neither will the damned be able then to see all their deeds at the same time.
On the contrary, A gloss on Job 8:22, "They... shall be clothed with confusion," says: "As soon as they shall see the Judge, all their evil deeds will stand before their eyes." Now they will see the Judge suddenly. Therefore in like manner will they see the evil they have done, and for the same reason all others.
Further, Augustine (De Civ. Dei xx) considers it unfitting that at the judgment a material book should be read containing the deeds of each individual written therein, for the reason that it would be impossible to measure the size of such a book, or the time it would take to read. But in like manner it would be impossible to estimate the length of time one would require in order to consider all one's merits and demerits and those of others, if one saw these various things one after the other. Therefore we must admit that each one sees them all at the same time.
I answer that, There are two opinions on this question. For some say that one will see all merits and demerits, both one's own and those of others, at the same time in an instant. This is easily credible with regard to the blessed, since they will see all things in the Word: and consequently it is not unreasonable that they should see several things at the same time. But with regard to the damned, a difficulty presents itself, since their intellect is not raised so that they can see God and all else in Him. Wherefore others say that the wicked will see all their sins and those of others generically at the same time: and this suffices for the accusation or absolution necessary for the judgment; but that they will not see them all down to each single one at the same time. But neither does this seem consonant with the words of Augustine (De Civ. Dei xx), who says that they will count them all with one glance of the mind; and what is known generically is not counted. Hence we may choose a middle way, by holding that they will consider each sin not instantaneously, but in a very short time, the Divine power coming to their aid. This agrees with the saying of Augustine (De Civ. Dei xx) that "they will be discerned with wondrous rapidity." Nor is this impossible, since in a space of time, however short, is potentially an infinite number of instants.
This suffices for the replies to the objections on either side of the question.
Source: Summa Theologica (New Advent)