The most powerful factor in determining tempo in hymn playing should be the nature of the message of the text. Simply explained, the mood of the text tends to pull the tempo of the hymn in one direction or the other, as follows:
Slower
reverent, expressive, meditative, majestic, thoughtful, solemn, humble, gentle, peaceful, fervent, devotional, calm, smooth, dignified, worshipful, reflective
Faster
jubilant, energetic, confident, bold, vigorous, exultant, triumphant, resolute, firm, spirited, cheerful, bright, praising