If you feel your dps is too low, its because all skills take one second and even chained skills that flow well are at 1 second per, so you are at the limitation of how much damage that one skill does plus your critical hit chance. If you want to raise your dps, all you have to do is a light attack and quickly cast a spell/skill with it and both the attack and spell will register under one second. Its called clipping and has been used in these kind of mmos that have active fighting/combat like age of conan and dc universe online. Your only other options to improve damage per second is to improve your critical hit chance and/or to lower a low cost ultimate that does damage. This doesnt include skill rank improvement since that is natural progression.

Always keep in mind that "instant" cast time spells are 1 second spells that grant you their effect instantly. For example, breath of life spell grants 400 health instantly,but the spell itself including animation and time to use the next skill is one second. However, some effects can bypass this effect. If crystal shards effect, from the sorc tree is activated, it can instantly cast and you can cast another spell in just under 1 second, but it still follows the one second rule give or take .10-.20. For this reason, sorcerer dps is high,it is basically a series of light attacks clipping into crystal shard then connecting to more clips and mage fury.

Some instant spells/skills frontload damage but are still one second cast. Silver bolts is the best example of this. The spell is instantly cast and the damage is given instantly and the animation finishes the one second cast. This is why it appears that this spell is great for chaining and maybe even feels like you are doing 2 actions in one second. Thats partially true. You can cast an offensive skill or attack+silver bolts and log in under a second but the dps would balance out after the damage is delivered and the animation finishes its motions.

Finally you have instant spells/skills that apply in the middle or end of that one second. Sunshield is an instant spell that triggers at the end of that one second. This means that instant cast spells have 3 ways they apply themselves. At the start, middle, or end. Now heres the cool part for some, or the problem for others: A light attack+a frontload damage skill+blocking eliminates the animation end sequence of a skill and allows you to quickly use another skill to improve your dps. For example: light attack+silver bolts+blocking(or block bashing)+silver bolts again takes about less time than light attack+silverbolts+silverbolts again. The reason this is like this is that the mechanics of the game let you hold block down and still be able to use skills. Try it next time you have a chance, you can literally hold block and cast spells while blocking. hope this helps.