Missing Width/Height Attributes and Optimizing Images

I am using v2.0.4 free version of this plugin and I really love it. I have worked hard on greatly improving my website’s page load speed time. After installing this plugin my websites ranking in gtmextrix.com got pinged for the following 2 reasons:

1) The following image(s) are missing width and/or height attributes.
2) Optimizing the following images could reduce their size by 6.7KiB (27% reduction

Examples of 1 are:
https://cdn.ratracegrad.com/wp-content/plugins/special-recent-posts/cache/srpthumb-p1476-100×55-no.jpg (Dimensions: 100 x 55)
https://cdn2.ratracegrad.com/wp-content/plugins/special-recent-posts/cache/srpthumb-p1401-100×55-no.png (Dimensions: 100 x 55)

Examples of 2 are:
Losslessly compressing https://cdn2.ratracegrad.com/wp-content/plugins/special-recent-posts/cache/srpthumb-p1401-100×55-no.png could save 3.0KiB (49% reduction). See optimized version
Losslessly compressing https://cdn3.ratracegrad.com/wp-content/plugins/special-recent-posts/cache/srpthumb-p1415-100×55-no.png could save 1.3KiB (22% reduction). See optimized version

My website is https://www.ratracegrad.com.

Is there anyway to adjust this plugin so that it automatically specifies a height/weight value for images instead of using auto in the CSS? I am using height 100 and width 55 and modified the plugins css to specify these values but it is not working. Also is there any way to have the thumbnails created modified so they avoid the image size compression message? Final question is will the PRO version resolve both of these issues?

Thanks.

https://www.ads-software.com/plugins/special-recent-posts/