And Arcane Spellsurge speeds up the casting time of the spell.
Give the sorcerer handy metamagic feats such as Empower Spell or Heighten Spell (or maybe Spell Energy Substitution). Also, giving some 1-round spell is not a bad idea when He knows Arcane Spellsurge.
Round 1
Cast a standard action spell and then, cast Arcane Fusion as a swift action.
or,
Cast Arcane Spellsurge as a swift action and then cast a 1-round spell or standard action spell modified by some metamagic feat(s). The latter is now a standard action.
Round 2 or later, cast one standard action spell (now a swift action) and a 1-round spell or standard action spell modified by some metamagic feat(s). The latter is now a standard action.
If you combine Arcane Spellsurge with Arcane Fusion/Greater Arcane Fusion, you can cast 4 spells per round.
With appropriate metamagic feats, a sorcerer can fight quite well without higher level attack spells. For example, Heightened Glitterdust is always useful. And if you empower 15d6 spell (Cacophonic Burst, Acid Storm), it may deal more damages than to a Horrid Wilting.