How to improve rgbdslamv2's 3D point cloud generation speed [closed]

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I'm using rgbdslamv2 with the following parameters

<param name="config/matcher_type" value="BRUTEFORCE"></param><!-- FLANN (not avail for ORB features), SIFTGPU (only for SIFTGPU detector)  or BRUTEFORCE-->
<param name="config/feature_extractor_type" value="ORB"/><!-- also available: SIFT, SIFTGPU, SURF, SURF128 (extended SURF), ORB. -->
<param name="config/feature_detector_type" value="ORB"/><!-- also available: SIFT, SURF, GFTT (good features to track), ORB. -->
<param name="config/detector_grid_resolution" value="3"/><!-- detect on a 3x3 grid (to spread ORB keypoints and parallelize SIFT and SURF) -->
<param name="config/max_keypoints" value="600"/><!-- Extract no more than this many keypoints -->
<param name="config/max_matches" value="300"/><!-- Keep the best n matches (important for ORB to set lower than max_keypoints) -->

<param name="config/min_sampled_candidates" value="4"/><!-- Frame-to-frame comparisons to random frames (big loop closures) -->
<param name="config/predecessor_candidates" value="4"/><!-- Frame-to-frame comparisons to sequential frames-->
<param name="config/neighbor_candidates" value="4"/><!-- Frame-to-frame comparisons to graph neighbor frames-->
<param name="config/ransac_iterations" value="100"/>
<param name="config/cloud_creation_skip_step" value="2"/><!-- subsample the images' pixels (in both, width and height), when creating the cloud (and therefore reduce memory consumption) -->

<param name="config/cloud_display_type" value="POINTS"/><!-- Show pointclouds as points (as opposed to TRIANGLE_STRIP) -->
<param name="config/pose_relative_to" value="largest_loop"/><!-- optimize only a subset of the graph: "largest_loop" = Everything from the earliest matched frame to the current one. Use "first" to optimize the full graph, "inaffected" to optimize only the frames that were matched (not those inbetween for loops) -->
<param name="config/backend_solver" value="pcg"/><!-- pcg is faster and good for continuous online optimization, cholmod and csparse are better for offline optimization (without good initial guess)-->
<param name="config/optimizer_skip_step" value="1"/><!-- optimize only every n-th frame -->

It runs but is extremely slow (processing just two frames in several minutes). Are there certain config parameters that I can tweak to get better performance?