yeh the best thing you can do is export to Audio as much as you can.
any sounds in there that don't have much automation just export to audio then delete them out the project.

if you have your full arrangement down - consider exporting whole stems. Running plugins like omnisphere you are gonna hit walls on any DAW or computer, especially stacking synths and FX plugins. Any CPU heavy instrument - get it exported and delete it out of there (use a save as incase u need to go back in and edit it)

Also with FL make sure you have the best buffer settings and also enable your smart disable ( Tools > macros > switch smart disable)  - turning it on basically turns off any plugins not being used during playback. - but once your project is condensed this is still futile.

The aim here is to export as much as you can and delete stuff out - I often find I have 7 or 8 revisions of projects all saved at different times incase I need to revisit an older project and say...change a note in my melody or something  (this isn't possible working with audio but if you keep older project files with the melody still in there you can go back in...change the note then export the audio again). make sure you delete everything that isn't being used -eg samples you put in there. Also change your computer settings from your control panel to high performance mode and also /ctrl,alt, delete -  open the task manager and close down any processes you aren't using. Often computers automatically open shit but keep them running in the background - for example my computer runs a screenrecorder in the background, dropbox, bullguard and some other shit -  I shut them all down completely from the task manager - that gives you a little more CPU. Ensure all internet windows are closed and if its a laptop that you are using it plugged in.

Don't get discouraged - every producer faces these issues man. Literally every track I do by the final mixdown I am changing something then exporting the full track to see if the change was right because playback is just impossible - just gotta keep at it. The fact is a lot of third party plugins  - like omnisphere, Izotope etc all chew up your CPU - even the best computers and laptops will feel thr brunt if projects are too plugin heavy.

I'm a fab filter whore! I cannot champion Fabfilter enough. I use practically all their plugins, the only one I don't have but want to buy is the Pro-MB.

The versatility, functionality and user interfaces of all their plugins are amazing. I really like the pro-q2 because of the sharp Q curves you can achieve, The mid-side EQ on it is great and there is also a feature where you can freeze the analyser and it will show any peaks - you can then highlight the waveform of the analyser and pull the specific peaks down- really handy. I also like the fact you can solo a frequency band - so I like to create large and narrow boosts then solo the frequency band hunt out any problematic frequencies!

The fab filter plugins are boss!!  I use their compressor, timeless and volcano a lot also!  And their Saturn plugin is probably in every single one of my projects also.

you have to understand that obtaining a good mix is all about balance.

You can have the best sounding kick in the world but if you crowd the space with muddy sub basses and leave it to low in a mix then the kick isn't going to work. Everything in a mix is about balance and finding room for your elements. Similarly if you have a great bass sound then clutter it with other melodic synths and FX. Its all about balance.
an analogy you can use is Think of it like an artist painting a landscape, you gotta find the space and see what works. what important elements need to be in the foreground, what needs to shape your background. You need contrast...you need quiet sounds, you need loud sounds, You need dynamics within your track. How everything works together is ultimately what shapes the outcome of your mix.

So if by 'more power' you mean how to make your track have punch and hit hard in a club then you need to get a good relationship between kick and bass. I mean, to me that is what essentially creates 'the power' in a dance track right? the bass, the low non-directional frequencies that you 'Feel' rather than hear. So if that is what you mean then the first thing I suggest you start with is a good kick and bass relationship.
'A good kick sit in a mix' ......again its all about space and balance. You need room for the kick to breathe, you may want some top end information to help your kick cut through the mix. like I said earlier you can have the best kick in the world but if you clutter that sample by adding too much to the track....that once perfect kick will sink into the mix.

remember 90% of mixing is all about level / volume balance. Focus first on the relationship in volume between all your sounds then dive into your advanced mixing techniques like compression etc.

Very insightful feedback! Thank you guys. A few more questions came up to mind when reading through your replies.

1) When cutting out the appropriate frequencies, is it better to use Low cuts/High cuts or Low shelfs/high shelfs? Part of me thinks that using cuts would get me a more clear sound because none of the frequencies would "spill" out. The other half of me thinks it's better to shelf the frequencies and allow it to "spill" out a little more gently so the overall song could be more full.

(This is confusing to me because I don't want my bass synth sub frequency to collide with my sub frequency, so using a low cut seems more appropriate)

2) Do you also cut out the frequencies of the kick within the sub and bass, or is sidechaining it good enough?

1) you basically need to trust your ears the best you can here without letting it get to crowded. Personally I compensate a lot. If I have a Sinewave sub bass and a bass sound I am generally brutal with the EQ's. on my main bass I will High pass quite high and keep the low frequencies occupied by my sub and kick -  then buss the basses together and compress them.  YOu should also be aware that most sounds with heavy low frequency info will have some sort of Low end resonance -  Grab an EQ and make a large but narrow boost and sweep across the sub frequency range very slowly - you will notice at some point in the soun (usually between 80-100hz ish) there will be a really resonant and unpleasant frequency. I like to tame these slightly with a narrow cut on the EQ. just helps tidy it up a bit. I also like to use mid / side EQ - Taking out the side information to around 90hz ish and highpassing the mids to whatever feels right for the track.

2) -  you know I used to always EQ my kick but now I never do! ive pretty much acquired a small bank of kicks that  I like to use and they have either been processed or I do not feel the need to process them. Sometimes id maybe do a low cut at 25 -30 HZ - sometimes look for that resonant low end problematic frequency or sometimes I just leave the sample as is.  I tend to use KICK by sonic academy and sometimes it can be quite weighty on the bottom end so I go in and tame it slightly with the EQ. Its all about how you think it sounds. If you feel the sub is clouding the kick....just sidechain, get your volumes right or even just highpass the sub around 10hz abouve where the kick is peaking and see how that sounds.

it is also important to understand that all 'Sub' frequencies are Sine Waves. Sine waves hold no harmonic content and all Low frequency information are sine waves. So why is that important? Well, lets assume that you are putting in sounds which occupy your sub frequencies, for example A sub bass (simple sine wave played at a low octave), Your kick, Your Tom percussion and you are also leaving in some sub frequency information on your bass sound. This is a really quick way to muddy up your low end, especially if you are tuning things and playing things on the same notes. Why? Because all you are doing is lining up sine waves and stacking them on top of each other. So a good way to keep your low end cleaner is to compensate the space. I usually end up having my sub frequencies ( 150hz / 170hz / even up to 300hz - depends how it sounds) occupied by one simple Sine Wave, every other sound, including my main bass will be high passed. (every other musical sound- not the kick obviously). The point is that your sub frequencies can very much be filled up by your kick drum and your sine wave bass. If your normal bass is losing to much punch, then get rid of the sine wave bass and use the sub frequencies from your main bass sound. Of course there are exceptions and keeping a lot of sub info can work sometimes but the fact is that you are just stacking up those sine waves down the bottom end.

for my sine wave bass I generally sum that to mono, couple it with my main bass sound, send them both to a buss where I will compress them or sidechain them. For the main bass I will either EQ out the entire frequency range where my sine wave bass is occupying or high pass it out to a point where the Sine wave and main bass don't seem to be cluttering each other. This can be hard in bedrooms because generally a low frequency waveform hasn't had chance to fully propagate before being reflected back at you. I guess its a case of trial and error and referencing tracks. The idea behind summing the lower frequencies to mono is to combat phase issues -  which are also a problem if you are stacking up those sub bass sine waves by having to much information down there.

Expression.

Any Art should be an expression of oneself. It is the process of creating something unique and putting it out there in the world to be loved or hated. There are fake artists but true art is always an expression of yourself to the world.

Learn to understand WHY you are doing something.
I am a fan of trial and error but one can lose their way by just throwing things on the mixer chains for the sake of it.
For example:
its really helpful to understand why you are compressing a sound, instead of just throwing loads of random compressors into your project. 
The more you learn the reasoning behind your mixing actions, the clearer and easier mixing becomes. You will soon be able to listen to a problematic signal and know what you need to do in order to fix it.

mixing is such a broad subject but I highly recommend going online and watching some series like Dave Pensados Into the lair videos. He runs through a whole load of mixing techniques and really delves deep into the subject. Id probably say everything I know about mixing has come from watching videos of professionals in action....mixed with some reading of course.

I like to mix as I go, however; I do fall into the trap of focusing to much on mixing processes before I actually have a track down. You should focus first on creating the main elements of your track; the music, the progressions, the hook.... whatever it may be. A track needs a foundation before getting too professor about the mixing. I recall countless times where I'm Eqing and compressing my drum track before I even have a concept for the track down haha!!  Focus on making an actual song first then once the body of the track is down focus on the intricate mixing stuff.