This is self-explanatory. JUBILANT occasions suggest faster tempos, setting a jubilant, lively, or possibly majestic mood.
The more SOLEMN occasions require hymn tempos that lean to the slower side, setting a meditative, prayerful, or reflective mood.
Other factors may still pull the tempo one direction or another. A hymn with very long phrases sung slowly at a solemn occasion will probably not be as effective as if it were sung at a quicker tempo (in spite of the nature of the occasion).